Wrapped in the second layer of steamed bun, and then sandwiched with tomato slices, onions, vegetables, pickles and other foods, so that you can eat the main and non-staple foods at the same time.
The earliest hamburgers were mainly composed of two buns and a beef pie. In modern hamburgers, besides beef patties or other patties (as long as they are fried or fried), there are butter, mustard, ketchup, salad dressing and so on. It is coated on the second layer of steamed stuffed bun, and then sandwiched with tomato slices, onions, vegetables, pickles and other foods, so that the main and non-staple foods can be eaten at the same time.