Hamburgers are customarily eaten as a sandwich, between two halves of a round bun. Mustard, mayonnaise, ketchup, and other condiments, along with garnishes of lettuce, onion, tomato, and sliced cucumber pickle, constitute the customary dressing. In the variation known as the cheeseburger, a slice of cheese is melted over the patty. The patty itself is often seasoned or augmented with chopped onions, spices, or bread crumbs before cooking.
According to United States Department of Agriculture (USDA) standards, hamburger meat may be designated either “hamburger,” “chopped beef,” or “ground beef.” It must be ground from fresh beef with no by-products or nonmeat extenders, but the USDA does permit the inclusion of loose beef fat and seasonings in meat labeled “hamburger.” Also, by law, hamburger and chopped or ground beef sold commercially may contain no more than 30 percent fat. Fifteen percent fat is regarded as the ideal proportion in terms of juiciness and flavour of the cooked product.
