In a mixing bowl, gently combine the ground beef with salt and black pepper. Divide the mixture into four equal portions and form them into patties, slightly wider than your buns as they will shrink during cooking. Slice the tomato and red onion into thin rounds. Wash and separate the lettuce leaves. Gather your cheese slices, buns, and all desired condiments.

If using a grill, preheat it to medium-high heat. If using a cast-iron skillet, place it over medium-high heat and add 1 tablespoon of cooking oil. Allow the grill or skillet to get thoroughly hot before adding the patties. This ensures a great sear.

Place the formed burger patties onto the hot grill or into the hot skillet. Cook for 3-5 minutes per side for medium-rare to medium doneness, depending on your preference. Only flip the patties once to allow a good crust to form. Avoid pressing down on the patties too much, as this squeezes out the flavorful juices.

During the last minute of cooking the patties, place a slice of cheddar cheese on top of each burger to melt. Meanwhile, lightly butter or brush the cut sides of the hamburger buns with a little oil. Place the buns cut-side down on the grill or in the skillet next to the patties, toasting them for 1-2 minutes until golden brown.

Carefully transfer the toasted bottom bun to a plate. Place a cheese-topped burger patty on top. Layer with fresh lettuce, tomato slices, and red onion rings. Add your desired condiments such as ketchup, mustard, and pickles. Finish by topping with the other half of the toasted bun. Serve your delicious classic American hamburger immediately!