I highly recommend you try Lamb's liver. It is sooooo delish! Lamb's Liver is best cooked on medium heat for a few minutes. A crock pot would be overkill & make lamb's liver tough.
Freeze the lamb's liver you can't use in a week & then slice up the rest thinly (about 1/4 inch). Coat in coconut flour mixed with salt & pepper and pan fry in lard/coconut oil. 1-2 min per side on med heat. Cook only what you will eat in one meal. You can store any extra sliced liver & coconut flour (separately!) in the fridge for a week.
I have cooked beef liver in crockpot and the result was very tough and dry. I recommend marinating the beef liver in apple cider vinegar for a couple of hours and patting it dry when you are ready to start cooking. Cut it in to strips and season it with salt and pepper along with any other spices you like (cumin, garlic powder, paprika etc...) Add coconut oil to a skillet over med-high heat and cook the liver only for a couple of minutes to avoid over cooking it. Remove the liver and add peppers and onions to the pan along with a little more ACV to pick up the brown bits stuck on the pan. My husband had never had liver before and he was pleasantly surprised when he tried it prepared this way. The use of ACV may sound a little odd but it aids in balancing out the strong liver flavor.
I've never tried it, but I do know that I've had the most success pan frying, high heat for short periods of time seems to create the texture I prefer. Even overcooking by a minute turns it into the texture of a rubber bands, I'd be scared to put it in a crock pot.