Hamburger is one of the most popular fast food dishes. It was invented in 1904 and its name derives from a piece of beef cooked in a specific way – in Hamburg style – by the German immigrants in the United States. Today hamburger is a type of sandwich, the base of which is a sliced roll, as well as fried ground pork formed into a circular shape. Onion, cucumber, a slice of cheese, tomato, a leaf of lettuce and sauces – ketchup and mayonnaise – are usually added to bread and meat. There are also different variations on a classic American burger. Beef cutlet can be replaced with a piece of breaded fish, grilled chicken and even vegetarian cutlet.