Mix the ground beef with salt and pepper. Knead and form into 4 equal-sized large patties.
Heat the clarified butter in a pan, and cook the patties on each side for 2-3 minutes. Slice the burger buns. Season the tomatoes with salt and pepper, then drizle with a little vinegar.
Spread the bottom of the buns with 1 tablespoon of mayonnaise, then top with the lettuce and pickles. Place one of the patties on top, then top with the sliced tomato and onion. Top with ketchup and then the sliced mozzarella. Top with more onions, the place the second patty, followed by pickles, tomato, and ketchup. Place the top half of the bun on top and serve.