Are kidneys kosher? If not, why so?

Question

Can someone please explain why it is what we often see intestines and liver used in kosher foods, but not kidneys?

Regarding the position of the organs, from what I can see in anatomy, the intestines are placed further back (in, say, a cow) than the kidneys, so I assume it's nothing to do with Gid Hanasheh.

Regarding chelev, if we can remove them from over the liver and intestines, surely we also can do it for the kidneys? Or does the smaller size of the kidneys make it not worth the trouble?

So what gives?
Could it be something to do with the Rabbinical view of the kidneys being linked to morality and emotion???

Answer 1

I found the following answer here:

"The Torah commands us to abstain from eating cheilev (Vayikra 3:17). These are specific fats which are found in the hindquarters of certain animals, sheep and cattle included. While the cheilev can be removed (using a method known as treibering), rendering the remainder of the meat kosher, this is a tedious and time-consuming task which can only be performed by professionally trained rabbis. It is not normally commercially viable to carry out this procedure. Additionally, due to the severity of the prohibition, some communities have adopted a custom of not using the hindquarters at all. This is the predominant custom in the USA, and it is followed by the OU.

As both round steak and kidneys are found in the hindquarters, they are included in this custom."

Answer 2

Yes kidneys are kosher.

A possible reason they are considered problematic is because they might be viewed as having ribui dam - an abundance of blood, due to their appearance. This would cause issues with the salting process. See Shulchan Aruch Yora De'ah 73 for details on this, under the laws of liver¹.

In Siman 74:1, the Mechaber and Rama discuss kidneys and both permit them. The Rama mentions there are some who have a custom to not cook the kidneys, and the Beit Yosef brings the Rokeach as forbidding them. The Darchei Moshe also says, as a result, that lechatchila, they should not be cooked².

So in addition to Avishai's reason (see also SA Y'D 105:8), this may also be a reason you don't see kidneys in some butchers.

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^{1 - To summarise, there is a gemara in Chullin 110B discussing how to prepare a liver for cooking. There is a principle of כבד אוסרת ואינה נאסרת - liver makes other pieces assur but does not itself become assur (due to its abundance of blood). Abaye asks if liver will assur other meat it is cooked with. Rabbeinu Tam understands his question to be "given that the proper way to kasher meat is by salting, but with a piece that is ribui dam, one shouldn't salt it but use another method, did the Rabbanim worry that by allowing liver in general, people might think you can prepare any meat without salting?". Rashi takes it further and says that Abaye is actually questioning if melicha works at all for these pieces (following the Rosh).}

^{2 - I would be very interested to see if there is any connection with these opinions and a kabbalistic idea regarding emotions etc. like you ask, but haven't found anything.}