If you have a steak medium to rare, such that it's still pink in the middle, is it kosher? At what point is meat cooked enough?
I'm assuming you are talking about steak which has been processed under rabbinical supervision.
Presently, in the US, with the exception of liver, all kosher meat is salted to remove problematic blood by the certifying agency before it hits the stores and restaurants. So meat which is edible does not have to be cooked "enough" and rare - or even steak tartare (raw) - is fine.
What Monica answered above, that it is 'meat juice'. To find out in much greater detail about this, see here:
- No matter what the source of the issur, the Ran asks: We clearly observe that blood continues to come out of meat even after the salting process is over. Indeed this blood is sometimes even redder than the blood that was originally expelled. Why do we permit this meat after the required time of salting, even though there blood still appears to be inside?
He gives two explanations :
A. The liquid which comes out of the meat after the period of salting is not blood but is called mohul (juice). The Gemora refers to it as chamra boser (the wine of the meat). In other words, although it may have the appearance of blood, it is not in reality blood that is ossur at all.
B. The issur of blood that comes out through the salting process is only forbidden Rabbinically, and the Rabbis limited their prohibition to blood that comes out of the meat during the period of salting . After that time, anything that comes out of the meat, although it may be blood, it is not within the Rabbinical enactment. Therefore it is blood of heter and not of issur.
This, based on the gemara in Chullin 113b.
Most of the other answers seem to be working under the assumption that the OP is basing the question on the prohibition against consuming blood (although this motivation is not stated in the question). Taking the question at its face value, however, the OP just wants to know how well meat needs to be cooked in order to be Kosher. As YDK's answer suggests (albeit somewhat vaguely), cooking has nothing to do with the Kashering process. Yes, we could get technical and discuss roasting meat in lieu of salting as a means of blood-removal, etc., but if the question is taken at face value, it is based on a faulty premise, probably due to a misunderstanding, that meat needs to be cooked 'X' amount in order to be Kosher. It does not.
You don't say why you think a rare steak might be a problem. I've heard others ask this question based on the prohibition of eating blood -- "hey, if we're not supposed to eat blood, then what about steaks?". I'm answering on the assumption that this is your reason for asking.
Chabad says that what's left in the meat after it's been kashered is juice, not blood, and ok. No sources cited, though I've heard this from a number of people (for what that's worth).
Raw, unsalted meat is completely kosher. Just rinse and eat. Shulchan Aruch Yoreh Deah siman 67 siff 2.
EDIT. The Shach in siman 76 s.k. 2 also point out that unsalted roasted meat even if only rare is also permitted to eat. The point of my original answer was to dispel any misconceptions about blood, but this edit will answer the assumed question more directly as pointed out in the comments.
One more point of clarification as pertaining to cooked, not roasted meat, is after salting the red juice is not considered blood,but called mohel, as pointed out by Monica. This is the Ashkenazi law lichatchila. For Sfardim however, if possible they should be putting the raw salted and washed meat into boiling, not warm or cold, water in order to seal in the red juice which the Rambam did in fact consider blood, and the Shulchan Aruch says to take into account, when possible. See siman 69 siff 19. This is process is called chalita.
I don't know any Sfardim who actually do this, whether at home or in restaurants (though some Teimanim do). So for all Acheinu bnei Hamizrach please comment or quote any modern day rulings, but this is what the Shulchan Aruch says and some people reading this question and these answers might find this interesting.
As others have pointed out, it doesn't have to be cooked at all. Another example of this is soaking raw muscle meat in vinegar - this is another method of kashering. So if you ever get the urge for kosher carpaccio... Although it seems like it's not such a straight forward process... Rambam discusses this although I don't have the reference handy at the moment.
י אֵין הַבָּשָׂר יוֹצֶא מִידֵי דָּמוֹ אֵלָא אִם כֵּן מוֹלְחוֹ יָפֶה יָפֶה, וּמְדִיחוֹ יָפֶה יָפֶה. כֵּיצַד עוֹשֶׂה: מֵדִיחַ הַבָּשָׂר תְּחִלָּה, וְאַחַר כָּךְ מוֹלְחוֹ יָפֶה יָפֶה, וּמַנִּיחוֹ בְּמִלְחוֹ כְּדֵי הִלּוּךְ מִיל; וְאַחַר כָּךְ מְדִיחוֹ יָפֶה יָפֶה, עַד שֶׁיֵּצְאוּ הַמַּיִם זַכִּים; וּמַשְׁלִיכוֹ מִיָּד לְתוֹךְ מַיִם רוֹתְחִין, אֲבָל לֹא לְפוֹשְׁרִין--כְּדֵי שֶׁיִּתְלַבַּן מִיָּד, וְלֹא יֵצֵא דָּם.
יא כְּשֶׁמּוֹלְחִין הַבָּשָׂר, אֵין מוֹלְחִין אוֹתוֹ אֵלָא בִּכְלִי מְנֻקָּב; וְאֵין מוֹלְחִין אוֹתוֹ אֵלָא בְּמֶלַח עָבֶה כְּחוֹל הַגַּס, שֶׁהַמֶּלַח הַדַּק כְּקֶמַח יִבָּלַע בַּבָּשָׂר וְלֹא יוֹצִיא דָּם. וְצָרִיךְ לְנַפַּץ הַבָּשָׂר מִן הַמֶּלַח, וְאַחַר כָּךְ יְדִיחֶנּוּ.
יב כָּל הַדְּבָרִים הָאֵלּוּ, לְבָשָׂר שֶׁצָּרִיךְ לְבַשְּׁלוֹ. אֲבָל לַצֳּלִי, מוֹלֵחַ וְצוֹלֶה מִיָּד. וְהָרוֹצֶה לֶאֱכֹל בָּשָׂר חַי--מוֹלְחוֹ יָפֶה יָפֶה וּמְדִיחוֹ יָפֶה יָפֶה, וְאַחַר כָּךְ יֹאכַל; וְאִם חֲלָטוֹ בְּחֹמֶץ, מֻתָּר לְאָכְלוֹ כִּשְׁהוּא חַי, וּמֻתָּר לִשְׁתּוֹת הַחֹמֶץ שֶׁחֲלָטוֹ בּוֹ, שְׁאֵין הַחֹמֶץ מוֹצִיא דָּם.
Mishne Torah Laws of Forbidden Foods 6:10-12
The meat is not freed of blood unless it has been thoroughly salted, and thoroughly rinsed. How is it done: first rinse the meat, and after that thoroughly salt it, and lay it in it's salt for the time it takes one to walk a mile; and after thoroughly rinse it, until the water runs clear; and throw it immediately into boiling water, but not just hot water -- such that it will whiten immediately, and blood will not come out.
When salting the meat, it is not salted except in a sieve, and it is salted only with salt like large sand grains, because salt fine like flour is absorbed into the meat and the blood isn't drawn out. And the meat should be shaken free of the salt, and then rinsed.
All of these things are for meat which is cooked ( in a vessel ). But for roasting, salt and roast immediately. And one who wants to eat raw meat -- salt it thoroughly and rinse it thoroughly, and afterwards eat it; and if one did chalita with vinegar, it is permissable to eat it raw, and it is permissible to drink the vinegar in which chalita was done, because the vinegar doesn't draw out blood.