I have been making my dogs' food, and am now incorporating organ meats. I like liver, but have never ventured into kidneys or hearts for myself. The dogs LOVE this stuff, however.
For a kidney (which I dismembered and will poach), the inside is heavily laced with a pure white fat. Is this the famous "leaf fat" that supposedly is better than lard for making pie crusts? Instead of throwing it out, can I render it in the poaching liquid and then use it in pastry?