In a small bowl, mix together the mayonnaise, ketchup, pickle relish, mustard, vinegar, sugar, and a pinch of salt. Stir until smooth and creamy. Set aside in the fridge while you prep everything else.

Wash and dry your lettuce. Slice your tomatoes and onions thin. If you want that classic burger-shop feel, keep everything ready to go before you start cooking.

Divide the ground beef into 4 equal portions and gently shape them into thin patties. Don’t overwork the meat. Keep them a little wider than the buns since they’ll shrink as they cook.

Lightly butter the insides of the buns and toast them in a skillet or on a griddle until golden brown. Set aside.

Heat a skillet or griddle over medium-high heat. Season the patties with salt and pepper right before they hit the pan. Cook for about 2–3 minutes per side, depending on thickness.

In the last minute of cooking, place a slice of American cheese on each patty and let it melt.

Spread the sauce on both sides of the toasted bun. Layer with lettuce, tomato, cheeseburger patty, and sliced onions. Add pickles if you want.