Classic Beef Burger with Caramelized Onions

1Heat a skillet over medium heat and add a little oil. Add the sliced onions and cook until caramelized, stirring occasionally, for about 15-20 minutes.

2Divide the ground beef (1 lb) into 4 equal portions and shape them into patties. Season with salt and pepper.

3Heat a grill or skillet over medium-high heat. Cook the beef patties for about 4-5 minutes per side, or until desired doneness.

4Toast the hamburger buns (4) on the grill or in a toaster until lightly browned.

5Assemble the burgers by placing a beef patty on the bottom bun, followed by a slice of cheddar cheese, caramelized onions, tomato (1) slices, lettuce leaves, pickles, ketchup, mustard, and mayonnaise.

6Top with the other half of the bun and serve hot.