Consommé (pronounced "con-som-AY") is a strong, rich, flavorful soup made by concentrating and clarifying stock. The word consommé means "completed" or "concentrated" in French.
Beef or veal consommé is made from brown stock, and has a rich, amber color produced by roasting the bones to make the stock, and also through adding some sort of tomato product, such as tomato paste, during the roasting process.
Chicken consommé is made from chicken stock, and is a pale yellow color. In each case, however, the distinguishing characteristics of a consommé are its strong flavor and its clarity.
Because it is high in gelatin, which is produced through the cooking of a protein called collagen which is present in bones, consommé also possesses a property called body. In this context, the term body refers to the fact that consommé has a richer, more weighty mouth-feel than ordinary broth.
Consommé is clarified through a process that involves simmering the stock along with a mixture of egg whites and lean ground meat called a clearmeat.
As the consommé simmers, the clearmeat solidifies into what is known as a raft which floats atop the liquid. The clearmeat draws proteins and other impurities that cloud a stock out of the liquid, leaving it perfectly clear.
One of the most important rules about making consommé is that it should not be stirred during the simmering process.
Stirring or otherwise agitating the liquid while it simmers will disrupt the clarification process, so the consommé will turn out cloudy.
That's why another key to making a good quality consommé is using a special pot with a spigot on the bottom. This allows the finished stock to be drained from the pot without disturbing the raft on top — which, again, would cause the consommé to be cloudy.
Another feature of its high gelatin content is that it will jell when it cools, making it the basis for preparing aspic. Because it seals off the surrounding oxygen, jelled consommé prevents the growth of bacteria that can cause spoilage and food poisoning. Thus storing foods in aspic (such as duck legs, for example) is a simple and early form of food preservation.
Note that cans of consommé you buy at the store aren't true consommé but rather ordinary broth which has been fortified by adding gelatin.