A Japanese hamburger is made with ground beef mixed with panko breadcrumbs, onions, ginger, and egg. It is cooked into patties and simmered in a sauce of sugar, sake, soy sauce and water rather than being served in a bun. The meat is formed into patties and browned in butter and oil before the sauce is added. It is topped with lettuce and optional grated daikon radish and served with rice or potatoes alongside the savory sauce.