Divide the ground beef into four equal portions and gently shape into patties slightly wider than the buns.
Press a small well into the center of each patty to prevent puffing.
Season the patties with salt and pepper just before cooking.
Preheat a stainless steel pan over medium-high heat and add oil.
Place patties in the hot pan and cook undisturbed until juices rise to the top.
Add sliced onions on top of the patties and sprinkle lightly with salt.
Flip burgers once, gently press to seal onions, and cook until juices run clear.
Add cheese slices and let melt.
Cook for a total of 6β8 minutes for medium doneness.
Assemble burgers with sauce, lettuce, pickles, tomato (optional), and buns.