^ see up above there somewhere, slow cooker 8 to 10 hrs and it will almost melt in your mouth. My mother used to use her pressure cooker years ago long before the slow cookers came out.
If you'll eat sausage, which are just the poo tubes of the creature, then you shouldn't have a problem with kidney.
We eat all the livers and hearts. Also roast all the bones and make a thick rich soup stock, makes for the best soup ever. No wild flavor once the fat is skimmed, so tasty. Pressure can in pints and it lasts all year.