Avoid those with dry spots or a dull surface. Kidneys should be used the day they're purchased, or store loosely wrapped in the refrigerator for up to 1 day. Before cooking, remove skin and any excess fat. Soaking helps reduce the strong odor in kidneys from more mature animals. See a general cookbook for details pertaining to the particular type of kidney you wish to cook.
All kidneys are a good source of protein, iron, phosphorus, vitamin A, thiamin and riboflavin.
Its popularity can be attributed to its full-bodied flavor. On the downside, it's an enthusiastic producer of flatulence. Unless you live in an area that grows kidney beans, you won't find them fresh but will have to settle for the dried or canned forms. Also called kielbasay or Polish sausage, this smoked sausage is usually made of pork, though beef can also be added. Kielbasa can be served separately or cut into pieces as part of a dish.