Soaking Liver in Milk
Soaking liver in milk before cooking it is optional. Soaking is done to make the flavor less "gamey" and to tenderize the meat. The lactic acid in buttermilk (and milk) tenderizes protein. To soak liver, put it in a dish and cover it completely with milk or buttermilk. Let it soak in the milk for 30 to 60 minutes, then pat it dry and proceed with the recipe.
Breading the Liver in Flour
Breading liver in a light coating of flour is optional. It's done to help the outside of the liver brown quickly. The starch in flour caramelizes quickly, giving liver a brown crust.
Cooking Temperature: According to the USDA, "organ meats should be cooked to a minimum internal temperature of 160 as measured with a food thermometer."
Storage: Cooked liver tastes best when eaten right after cooking. However, you can store it in the refrigerator for up to 3 days.