In a large mixing bowl, combine the ground beef, salt, black pepper, and garlic powder. Mix gently until just combined. Divide the mixture into two equal portions and form each portion into a round patty, about 3/4 inch thick.

Cooking the Patties

Preheat a grill or skillet over medium-high heat. Cook the patties for about 4-5 minutes on one side. Flip the patties and cook for another 3-4 minutes for medium doneness. If using cheese, place a slice on each patty during the last minute of cooking to melt.

Assembling the Burger

Toasting the Buns

While the patties are cooking, split the burger buns and toast them on the grill or in a toaster until golden brown.

Preparing the Vegetables

Wash and dry the lettuce leaves. Slice the tomato into thick rounds and the onion into thin slices.

Building the Burger

On the bottom half of each toasted bun, place a lettuce leaf, followed by the cooked patty (with cheese if used), a slice of tomato, and a few onion rings. Add ketchup, mustard, and mayonnaise to taste. Top with the other half of the bun.