Is being a vegan completely okay according to halacha?
Even if a vegan is not eating anything traif (non-kosher), perhaps it's not truly correct because you are not following the commandments to domesticate animals and eat meat.
There's no specific mitzvah to eat meat (except in connection with certain sacrifices, but those are in abeyance until the Holy Temple is rebuilt - may it be soon).
There is a mitzvah to enjoy Shabbat and holidays, and for most people that includes eating meat. But it's somewhat subjective; if for a particular individual that would be a burden rather than a pleasure, then by all means they should eat something else.
The real issue, perhaps, is more one of outlook. If a person chooses to be a vegetarian/vegan for health reasons, for example, then there's nothing wrong with that. On the other hand, if their rationale is that humans have no right to use animals for food or the like, then we need to ask: why are they trying to be more merciful than G-d?
Contrary to what many frum Jews believe, it is not required to eat meat on Shabbos and Yom Tov. So as far as the dietary aspect of veganism goes, it is permissible.
But many interpret veganism to mean that one does not wear clothes made from animals.
There is probably no problem with a Jewish woman being completely vegan in this sense (though there's the issue of owning mezuzot). But men are required to use tefillin (made from leather) and tallit (wool).
There are in fact "kosher vegans" who eat vegan but use kosher tefillin. Rabbi Shmuley Yanklowitz has started an organization to support them (called Shamayim V'Aretz.) The head of Jewish Vegetarians of North America, Richard Schwartz, is an Orthodox Jew (who is at least vegetarian).
The ideological aspect is potentially problematic. Many vegans believe it is inherently wrong to ever use animals for food. So if this is the motivation for being vegan, it contradicts Judaism, which permits certain animal foods. For this reason, some say it is forbidden to be a vegetarian or vegan for "animal rights" reasons. However, because factory farm conditions cause unnecessary suffering to animals, and unnecessary suffering is forbidden (the mitzvah of ba'alei tzaar chaim), one could be vegan to avoid benefiting from or supporting probable violations of this mitzvah.
Another consideration is that veganism is an all-encompassing lifestyle and ideology for many people. A possible danger is that Jewish vegans will find this lifestyle and community satisfying and no longer feel the need to believe in or observe Judaism. This shouldn't prevent Jews from becoming vegan for reasons of health or ba'alei tzaar chaim, but they should avoid getting too invested in vegan ideology, community, etc.
My answer will address both vegan and vegetarianism.
The Bible is fairly clear that God's ideal diet for all of creation was vegetarianism. And that at some point He allowed the consumption of meat, under various caveats, and usually with disapproving tones. Some people erroneously try and say that mankind was given dominion over the animals, and therefore we are allowed to eat them, however, when that dominion was given, we weren't allowed to eat animals until many hundreds of years later. So whatever that "dominion" is, it has nothing to do with eating animals. Let's trace vegetarianism in the Bible, and then we will go to Rabbinic comments endorsing vegetarianism.
כח: וַיְבָרֶךְ אֹתָם, אֱלֹהִים, וַיֹּאמֶר לָהֶם אֱלֹהִים פְּרוּ וּרְבוּ וּמִלְאוּ אֶת-הָאָרֶץ, וְכִבְשֻׁהָ; וּרְדוּ בִּדְגַת הַיָּם, וּבְעוֹף הַשָּׁמַיִם, וּבְכָל-חַיָּה, הָרֹמֶשֶׂת עַל-הָאָרֶץ. כט: וַיֹּאמֶר אֱלֹהִים, הִנֵּה נָתַתִּי לָכֶם אֶת-כָּל-עֵשֶׂב זֹרֵעַ זֶרַע אֲשֶׁר עַל-פְּנֵי כָל-הָאָרֶץ, וְאֶת-כָּל-הָעֵץ אֲשֶׁר-בּוֹ פְרִי-עֵץ, זֹרֵעַ זָרַע: לָכֶם יִהְיֶה, לְאָכְלָה. ל: וּלְכָל-חַיַּת הָאָרֶץ וּלְכָל-עוֹף הַשָּׁמַיִם וּלְכֹל רוֹמֵשׂ עַל-הָאָרֶץ, אֲשֶׁר-בּוֹ נֶפֶשׁ חַיָּה,
28 And God blessed them [mankind]; and God said unto them: 'Be fruitful, and multiply, and replenish the earth, and subdue it; and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that creepeth upon the earth.' 29 And God said: 'Behold, I have given you every herb yielding seed, which is upon the face of all the earth, and every tree, in which is the fruit of a tree yielding seed--to you it shall be for food; 30 and to every beast of the earth, and to every fowl of the air, and to every thing that creepeth upon the earth, wherein there is a living soul, [I have given] every green herb for food.' And it was so.
So in the beginning, God only sanctioned one diet for all life, that of vegetarianism. This holds true even to the time of Noach, for in the ark the Noach and his family. It's a verse that is often glossed over, but Noach and his family ate the same food as the rest of the animals, which we find from a later verse shows that Noah and every animal on the ark were still vegetarian.
כא וְאַתָּה קַח-לְךָ, מִכָּל-מַאֲכָל אֲשֶׁר יֵאָכֵל, וְאָסַפְתָּ, אֵלֶיךָ; וְהָיָה לְךָ וְלָהֶם, לְאָכְלָה.
21 And take thou unto thee of all food that is eaten, and gather it to thee; and it shall be for food for thee, and for them.'
How do we know they were still vegetarians? Because after the flood God says that Noach can now eat meat, just like the green of the field that was already commanded to be eaten. And there's a caveat, now that meat is permissible, animals are now going to be scared of humans. When all life was vegetarian, there was no need for the animals to be scared
ב וּמוֹרַאֲכֶם וְחִתְּכֶם, יִהְיֶה, עַל כָּל-חַיַּת הָאָרֶץ, וְעַל כָּל-עוֹף הַשָּׁמָיִם; בְּכֹל אֲשֶׁר תִּרְמֹשׂ הָאֲדָמָה וּבְכָל-דְּגֵי הַיָּם, בְּיֶדְכֶם נִתָּנוּ. ג כָּל-רֶמֶשׂ אֲשֶׁר הוּא-חַי, לָכֶם יִהְיֶה לְאָכְלָה: כְּיֶרֶק עֵשֶׂב, נָתַתִּי לָכֶם אֶת-כֹּל.
2 And the fear of you and the dread of you shall be upon every beast of the earth, and upon every fowl of the air, and upon all wherewith the ground teemeth, and upon all the fishes of the sea: into your hand are they delivered. 3 Every moving thing that liveth shall be for food for you; as the green herb have I given you all.
It is worth noting that as soon as God decides not to flood the world again, He immediately launches into the permissibility to eat meat. This eating of meat allowance applies not only to humans, but also to the animals. And the placement of this allowance seems can seem out of place if one doesn't focus on it. As Rabbi Soloveitchik points out, it's possible that one of the reasons that God flooded the earth was because there were large segments of humans and animals who were becoming carnivorous. And therefore it could be that God sanctions meat eating in order that He doesn't have to destroy the world again.
From this point the topic of diet isn't discussed much. Eventually the Israelites are redeemed from Egypt, and there is further meat restriction. Noach and his family were allowed to eat meat from all animals (with caveats of fear, and not eating flesh from a living animal, etc), but the Israelites were to be limited to eating only vegetarian animals. And in instances in which the Israelites demand meat (rather than just crying out for hunger in general), God responds in a very unhappy way, and always describes the desire to eat meat with the Hebrew word תַּאֲוָה, which means to lust. In general, the word lusting can either be negative or positive depending on context, but with meat eating it's always negative. The first story happens in numbers. There's the initial lusting of the people, followed by a lot of dialogue, back and forth, and finally a plague due to the lust for meat.
ד וְהָאסַפְסֻף אֲשֶׁר בְּקִרְבּוֹ, הִתְאַוּוּ תַּאֲוָה; וַיָּשֻׁבוּ וַיִּבְכּוּ, גַּם בְּנֵי יִשְׂרָאֵל, וַיֹּאמְרוּ, מִי יַאֲכִלֵנוּ בָּשָׂר...לג הַבָּשָׂר, עוֹדֶנּוּ בֵּין שִׁנֵּיהֶם--טֶרֶם, יִכָּרֵת; וְאַף יְהוָה, חָרָה בָעָם, וַיַּךְ יְהוָה בָּעָם, מַכָּה רַבָּה מְאֹד.לד וַיִּקְרָא אֶת-שֵׁם-הַמָּקוֹם הַהוּא, קִבְרוֹת הַתַּאֲוָה: כִּי-שָׁם, קָבְרוּ, אֶת-הָעָם, הַמִּתְאַוִּים.
4 And the mixed multitude that was among them fell a lusting; and the children of Israel also wept on their part, and said: 'Would that we were given flesh to eat!...33 While the flesh was yet between their teeth, ere it was chewed, the anger of the LORD was kindled against the people, and the LORD smote the people with a very great plague. 34 And the name of that place was called Kibroth-hattaawah, because there they buried the people that lusted.
Originally God was only going to sanction the eating of meat when one brings a sacrifice to the tabernacle. But God changes His mind due to the fact that the Israelites will lust after meat, and that since the tabernacle may be too far away, there is a risk that they might sin and slaughter the animal in their gates rather than make the pilgrimage to the tabernacle. So if one lives too far from the tabernacle, one may slaughter an animal to eat it in their town. However, it also implies that if you live close to the mishkan, you can't eat meat without sacrificing it at the altar in the mishkan.
כ כִּי-יַרְחִיב יְהוָה אֱלֹהֶיךָ אֶת-גְּבֻלְךָ, כַּאֲשֶׁר דִּבֶּר-לָךְ, וְאָמַרְתָּ אֹכְלָה בָשָׂר, כִּי-תְאַוֶּה נַפְשְׁךָ לֶאֱכֹל בָּשָׂר--בְּכָל-אַוַּת נַפְשְׁךָ, תֹּאכַל בָּשָׂר. כא כִּי-יִרְחַק מִמְּךָ הַמָּקוֹם, אֲשֶׁר יִבְחַר יְהוָה אֱלֹהֶיךָ לָשׂוּם שְׁמוֹ שָׁם, וְזָבַחְתָּ מִבְּקָרְךָ וּמִצֹּאנְךָ אֲשֶׁר נָתַן יְהוָה לְךָ, כַּאֲשֶׁר צִוִּיתִךָ--וְאָכַלְתָּ, בִּשְׁעָרֶיךָ, בְּכֹל, אַוַּת נַפְשֶׁךָ.
20 When the LORD thy God shall enlarge thy border, as He hath promised thee, and thou shalt say: 'I will eat flesh', because thy soul lusts to eat flesh; thou mayest eat flesh, after all the lust of thy soul. 21 If the place which the LORD thy God shall choose to put His name there be too far from thee, then thou shalt kill of thy herd and of thy flock, which the LORD hath given thee, as I have commanded thee, and thou shalt eat within thy gates, after all the lust of thy soul.
To those that might view this "lusting" being neutral, one should contrast it to how God speaks of vegetarian foods. The distinction between how God views meat eating vs eating vegetarian becomes abundantly clear when contrasted with how God describes the latter.
ז כִּי יְהוָה אֱלֹהֶיךָ, מְבִיאֲךָ אֶל-אֶרֶץ טוֹבָה: אֶרֶץ, נַחֲלֵי מָיִם--עֲיָנֹת וּתְהֹמֹת, יֹצְאִים בַּבִּקְעָה וּבָהָר. ח אֶרֶץ חִטָּה וּשְׂעֹרָה, וְגֶפֶן וּתְאֵנָה וְרִמּוֹן; אֶרֶץ-זֵית שֶׁמֶן, וּדְבָשׁ. ט אֶרֶץ, אֲשֶׁר לֹא בְמִסְכֵּנֻת תֹּאכַל-בָּהּ לֶחֶם--לֹא-תֶחְסַר כֹּל, בָּהּ; אֶרֶץ אֲשֶׁר אֲבָנֶיהָ בַרְזֶל, וּמֵהֲרָרֶיהָ תַּחְצֹב נְחֹשֶׁת. י וְאָכַלְתָּ, וְשָׂבָעְתָּ--וּבֵרַכְתָּ אֶת-יְהוָה אֱלֹהֶיךָ, עַל-הָאָרֶץ הַטֹּבָה אֲשֶׁר נָתַן-לָךְ.
For the Lord thy God bringeth thee into a good land, a land of brooks of water, of fountains and depths, springing forth in valleys and hills; a land of wheat and barley, of vines and fig-trees and pomegranates; a land of olive- trees and honey; a land wherein thou shalt eat bread without scarceness, thou shalt not lack anything in it... And thou shalt eat and be satisfied, and bless the Lord thy God for the good land which He hath given thee.
Among many similar statements by the prophets are:
יד וְשַׁבְתִּי, אֶת-שְׁבוּת עַמִּי יִשְׂרָאֵל, וּבָנוּ עָרִים נְשַׁמּוֹת וְיָשָׁבוּ, וְנָטְעוּ כְרָמִים וְשָׁתוּ אֶת-יֵינָם; וְעָשׂוּ גַנּוֹת, וְאָכְלוּ אֶת-פְּרִיהֶם. טו וּנְטַעְתִּים, עַל-אַדְמָתָם; וְלֹא יִנָּתְשׁוּ עוֹד, מֵעַל אַדְמָתָם אֲשֶׁר נָתַתִּי לָהֶם--אָמַר, יְהוָה אֱלֹהֶיךָ.
I shall return my people from captivity, and they shall build up the waste cities and inhabit them, and they shall plant vineyards and drink the wine from them, and they shall make gardens and eat the fruit from them, and I shall plant them upon their land.
בְּנוּ בָתִּים, וְשֵׁבוּ; וְנִטְעוּ גַנּוֹת, וְאִכְלוּ אֶת-פִּרְיָן.
Build ye houses and dwell in them, and plant gardens and eat the fruit of them.
I am not aware of any instance where eating vegetarian is described with the word lust, nor am I aware of God ever waxing poetic with descriptions of meat eating like in the above passages.
As for Rabbinic views endorsing vegetarianism, here is a good summation, one can follow the link to the source at the bottom if they want access to the sources for themselves.
Joseph Albo (15th century, Spain), in his Sefer ha-Ikkarim, explains that the consumption and slaughter of animals lead to the development of many negative traits in man. As man consumes more and more meat, Albo claims, he becomes emotionless and is transformed into a merciless killer, with an increasingly weaker connection to his soul. Yet, Albo warns his readers against thinking that man and animal are equals. The concern for animal welfare, which he feels comes from an equalization of man and animal, is not the reason, he argues, to renounce the consumption of meat. Such thinking is not only morally erroneous, but repugnant.
Rabbi Abrahaim Isaac Kook, in his treatise entitled Hazon ha-Tsimhonut ve-ha-Shalom (The Vision of Vegetarianism and Peace), advocates for vegetarianism with powerful arguments affirming even the conventional vegetarian contentions. R. Kook claims that vegetarianism is a Torah ideal and that many mitsvot, such as shehitah, sha’atnez, and kisuy ha-dam, are based on this ideology. Despite this belief, however, R. Kook has reservations whether vegetarianism should be practiced out of moral conviction, and instead feels that vegetarianism should be practiced only in the context of other reasons, such as dislike for the taste of meat.
R. Soloveitchik has no reservations concerning vegetarianism, and affirms it both as an ideal and a practice. He believes that all life, even animal life, is sanctified. In explaining his point, R. Soloveitchik cites Sanhedrin 59b, which says that Adam did not eat meat, and it was only when Noah entered the biblical narrative that meat was permitted. Commenting on this, R. Soloveitchik states that the natural reality of Adam’s distaste for meat became the ethical norm with the phrase, “and it was so.” R. Soloveitchik explains, “Thus the verse concludes ‘and it was so’: the ethical norm became a behavior pattern, an expression of the ontic order.” The ethical imperative against eating meat becomes the physical and biological reality of man’s world—no one would eat meat. Yet, as the history of man continues through dor ha-mabbul (the generation of the flood), man begins to overreach himself, to take what is not his, including the life of another living being. Thus, God eventually gives in and allows Noah to eat meat: “Every moving thing that lives shall be food for you; even as the green herb have I given you all things.” R. Soloveitchik explains, “At once the Torah began to regulate the ‘murder’ of other lives, to restrict its practice by complicating the procedure… ‘[the Torah succumbed to the Evil Inclination by allowing for certain things, hence] the Torah provided for human passions: [reasoning that] it is better for Israel to eat the flesh of animals that are ritually slaughtered than the flesh of animals which have perished [i.e. nevelot (the dead unslaughtered carcass of an animal)]’ (Kiddushin 21b-22a).” R. Soloveitchik explains that the Torah allows man to fulfill his desire for meat, but out of a care for animal life, it complicated the process of acquiring meat.
R. Soloveitchik, unlike Rabbis Albo and Kook, takes a very strong position regarding carnivorous practices. He calls it “ta’avah” (lust) and an “illicit demand.” “The insistence upon flesh, his [man’s] lusty carnal desire,” R. Soloveitchik says, “arouses the divine wrath.” Those who choose to eat meat, the “animal hunters and flesh-eaters” are “people that lust.” This strong language is not found in the writings of Rabbis Kook and Albo; they are only harsh towards those who ideologically refuse to eat meat.
R. Soloveitchik’s severe stance is based on the story of Kivrot ha-Ta’avah (the graves of those who craved [meat]), the tragic account of Benei Yisrael’s lust for animal flesh. In the story of Kivrot ha-Ta’avah, Benei Yisrael protest to God and Moshe, demanding meat instead of the manna that God had been supplying. Moshe prays to God and, although God is angry with the people, He gives them the meat. Once satiated, the people die as a result of a plague that God sends. In his explanation of this story, R. Soloveitchik says that God admonished Israel for their dissatisfaction with their vegetarian diet of manna and their need to have meat. Deuteronomy 12:20, in discussing God’s commandments for when Benei Yisrael will live in the land of Israel, supports this point: “And you shall say: ‘I will eat flesh’, because your soul desires to eat flesh; you may eat flesh, after all the desire of your soul.” The Torah uses the word “desire” to characterize man’s hunger for meat; it is the dominating physical desire. Hence, according to R. Soloveitchik, vegetarianism should be practiced, yet man, too desirous for meat, refuses to stop eating animal flesh.
Moving from the theoretical level to a practical level, R. Soloveitchik defends his strong opinion against potential halakhic challenges. First, the Torah’s sanction and, according to most commentators, desire for sacrifices is problematic in the face of the aforementioned opinions. Is it possible that the Torah really cares about animal welfare and yet still commands Benei Yisrael to slaughter animals wantonly to God? In response, R. Soloveitchik posits that sacrifice is the returning of one’s body—God’s property—to its Owner out of a debt to Him for His priceless gift of life, yet the ethos of sacrifice is the value for life. Man, in reciprocation for the life given to him, must offer up his life, but paradoxically cannot since by expressing thanks to God, man is stating his value for his own life. Hence, God forbids human sacrificial suicide, and, as a replacement, commands that an animal should be placed on the altar. In support of his idea, R. Soloveitchik brings a unique interpretation of the story of the Binding of Isaac: Abraham sacrifices Isaac to pay the debt that he owes his Creator, Who finally granted him the life of his child. But the angel stops Abraham from slaughtering his son, since God values life, and Abraham sacrifices a ram in place of Isaac. A life needed to be taken in order to reciprocate for the precious gift that God gave Abraham, but the life of Isaac—of every man—has more moral value than that of an animal because, R. Soloveitchik suggests, men are the messengers of God to the world. Similarly, Abarbanel, in his introduction to Leviticus, explains that different sacrifices symbolize man’s redemption of his life. For example, an olah (burnt offering) is meant to symbolize man giving over his whole body, and the blood splashed onto the altar is meant to symbolize man’s life force. However, outside of this clear requirement to return, through sacrifices, the infinite debt that man owes to his Creator for giving him life, sustaining him, and helping him, the Torah may still frown upon the consumption of meat outside of the context of sacrifice.
So is being vegan or vegetarian "kosher"? The answer is most definitely yes. However, this is not normative Jewish practice, and nearly every Jewish community has a practice of regularly eating meat. And the vast majority of poskim encourage meat eating, especially when it comes to holy days like Yom Tovim and Shabbath. However, there is a lot of misconceptions that people have about meat eating in the bible. There are those who think that eating meat is commanded, or even encouraged. When in reality, the truth is closer to the Bible preferring vegetarianism, and begrudgingly allowing the eating of meat. And noted modern Rabbis who are vegetarian for these (and other) reasons even include the former chief Rabbi of England, Sir Rabbi Jonathan Sacks.
Even if you are actually completely vegan, meaning not only not eating meat or any other product derived from animals (such as milk), but also checking for bugs and not using utensils that were used for meat or other non-kosher things, it wouldn't be enough.
Keep in mind that terefot are not the only halacha in cashrut. For example, there's also nesech wine, orla and bishul oved cohavim.
There's also the question of whether abstaining from meat is permissible.
First of all, there's no obligation to domesticate animals like you say, but if you do want to eat meat you need to slaughter. While there's no specific commandment to eat meat, there is a commandment to be happy on iom tov and joyful on shabat. It is explained that this is achieved by eating meat meals. Because of this, people make a point on eating meat on holidays, shabat and at other festive meals such as berit mila or weddings. On the other hand, you could argue that someone may dislike meat and hate its taste, so eating meat on shabat not only wouldn't achieve the proper goal but would in fact have the opposite effect.
Most religious Jews do eat meat, but I have heard that there are some that don't. I met one religious Jew who was actually vegan (we ordered pizza and he ordered one without the cheese) and one rav who had a certain revulsion to meat after a visit to a chicken slaughter house, so he would eat only a little meat on shabat just to fulfil the halacha.
I have heard some answers from rabanim from people dwelling with this apparent stira (being vegan). The conclusion was that while you shouldn't look to follow this path lechatehila or convince people to do it, there are those unique people that are vegan (or vegetarian) and I didn't see them trying to convince them otherwise.
Also, on a general note, the individual's health should always come first. It is common for vegans to lack some kind of vitamin and needed supplements, or they put their health at risk because of the lack of something in the blood.
R. Chaim Berlin has a responsum relating to this.
He was asked about the permissibility of joining an animal cruelty [prevention] group and refraining from using things which come from animals. The questioner had apparently suggested that it should be forbidden because R. David Helevi Segal writes that the Sages do not have the ability to prohibit something that the Torah explicitly permits. (Thus, if the Torah explicitly permits animal products we can't renounce them.)
R. Berlin responded that R. Segal was only referring to the Sages' authority to create a prohibition on all of Israel. That cannot be done if the Torah explicitly permits something. However, every individual always retains the right to add any prohibitions for himself by taking a vow. The only thing is that the Classical sources frown upon taking vows (unless necessary):
Nishmat Chaim (the one volume edition) # 120
אשר שאל אם מותר להסתפח לחברת צער בעלי חיים ולהנזר מדבר הבא מן החי והוא נגד ד' הט"ז דאין כח לחכמים לאסור מה שהתירה תורה בפירוש
נראה דעד כאן לא אמר הט"ז אלא דאין כח ביד חז"ל לגזור איסור לכל ישראל על דבר שפירשה התורה בפירוש להיתר אבל מי שירצה לאסור על עצמו אכילת בשר אין זה בכלל דברי הט"ז והרי הוא ככל הנדרים שכתבה תורה בפירוש איש כי ידר נדר או השבע לאסר אסר על נפשו לא יחל דברו אלא שחובה להתרחק מן הנדרים והנודר כאלו בנה במה ונקרא רשע כדתנן בפ"ק דנדרים ט' א' כנדרי רשעים וביו"ד סי' ר"ג
It would appear, then, that R. Berlin's only concern was with the taking of a vow. If, however, one simply refrains from using animal products without formalizing it as a vow, R. Berlin would presumably have no objection.
R Gil Student writes here that R Gedaliah Felder was opposed to Jews being vegetarians because
this attitude comes from gentile sources and contradicts the spirit of Judaism. Therefore, adopting ideological vegetarian attitudes violates the prohibition against following gentile practices.
See the original for the full Hebrew text of his responsa.