Difficulty: Easy - for beginners
Jewish Rye bread
Grill the hamburgers on an outdoor grill. Slice the onion and saute in olive oil on the stove. Butter each slice of bread on one side only. Place that side down in a large pan/griddle on top of the stove. Allow the bread to cook for a few minutes until it becomes slightly browned. Place the hamburger on top of one of the slices, then add a slice of swiss cheese and sauteed onions. Place the other slice of bread on top so that the buttered side is on the outside. Flip the sandwich as needed and cook until the bread is as toasted as you desire. Then remove the sandwich and add tomatoes and ketchup on top of the onions.