The tripe found in most markets today is the muscular lining of beef stomach, though pork and sheep also fall under the definition. There are two beef stomach chambers and three kinds of tripe, all of which are tough and require long cooking (about 12 hours). The best tripe is from the second stomach chamber and is called honeycomb tripe because the inner side has a pattern similar to a honeycomb. It's the most tender and subtly flavored. Pocket tripe is cut from the end of the second stomach chamber and is shaped like a pocket with a honeycombed inside. The least desireable plain or smooth tripe comes from the first stomach.
Tripe is available fresh (which is actually partially cooked) in most supermarkets. Choose tripe with a plale off-white color. Tripe is also available pickled and canned.
Refrigerate up to 1 day.