A consommé is a meat, game, poultry, or fish stock from which all impurities have been removed, leaving an almost-transparent broth. The most common consommés are made from beef broth (see marmite) with the addition of tomatoes, game stock (see fond de gibier), or white poultry stock (see fond de volaille blanc). Whatever the variety, it always begins with an intensely flavored and richly colored broth made with lean meat, highly gelatinous bones such as knuckle, feet, and shin, and blackened onions (oignons brûlées). The purity and flavor are achieved through a two-step operation by which the broth is clarified. This occurs when a broth is enriched through the addition of lean chopped meat, egg whites, finely chopped vegetables, herbs, and, sometimes, spices, and then gently simmered. As the mixture simmers, particles that might otherwise cloud the broth are entrapped by the eggs’ albumen and blood in the added ingredients.