MEAT FROM THE OTHER PARTS OF THE ANIMAL
The meat as we know it is basically a pack of muscles with some fat here and there. However, animals not only carry muscles, but also other tissues and organs that we can eat. These are the things that have been called offal, variety meats, innards - in other words, things like liver, heart, kidney and similar pieces of the animal that some people like and others find objectionable. Why can we eat these organs? To start with, they also contain muscles, although they are not in the same shape as the skeletal muscles we usually eat. In addition, there is also a lot of connective tissue surrounding and blending with these muscles. This has to be kept in mind when attempting to cook the organ meat - we need to dissolve the connective tissue into an edible mass by cooking it slowly while keeping it moist. Pretty much like cooking tough cuts of meat, as we discuss on other pages. This thing being equal, the organs must also usually be trimmed prior to cooking.
Then is the issue of the special organs, like liver, which don't contain a lot of connective tissue or have a finer form of it due to less strain applied to them during the life of the animal. Liver cannot be cooked for too long or it will become dry and brittle. Its delicate texture requires just a short while of cooking, and it has an interesting special flavor that most people enjoy. Some livers are produced in a special way, e.g. foie gras, which comes from poultry that has been overfed. This process can be said to be a sort of fattening up of the bird, and the liver (being the primal organ for food metabolism) will collect much of the food that the bird eats. If the feeding is really exaggerated, the liver will grow to a large size while collecting lots of small fat particles that give a smooth texture and a nice delicate flavor. Due to this large amount of fat, foie gras liver doesn't look as it normally does (red colored) but it's pale and should have a semi-soft feeling when pressed with a finger (not too soft and not too hard, or its fat content is not the optimal). Foie gras liver is simply prepared by a brief sautéing of thick slices in a hot pan (no fat!) just so the surface is brown and the inner part is warm. It should be served right away!
Other connective tissue-rich organs can also be used in cooking, and because of their nature they will provide gelatin to the dish. The more gelatin we get, the more body the dish will have. Gelatin, when cooled down and in sufficient amount, will make the liquid stiff enough to create a jelly-like dish containing various cuts of meat, if so desired. Of course, some cuts, like ears or tails, can be cooked solely for their taste, either in a long cooking process that will make them tender, or just in a brief cooking that will retain some of their crunchiness.
So we can eat muscle tissue, connective tissue, epithelial tissue (liver); what about fat tissue? Surely, this is not something that we usually put in our mouths as it is. However, there are some exceptions. The big membraneous layer that surrounds the organs in our abdominal cavities is quite fat, and it can be eaten. It is called caul fat. It can be used to wrap the foods when cooking, so the fat will dissolve and penetrate the meat tissue, giving it more moisture and flavor. Also other animal fats are used in cooking, including suet (from around the kidneys), skin fat, back fat, belly fat. They have all found uses in the culinary world, perhaps in an attempt to avoid wasting the expensively bred animals.