Ingredients
Method
- Preheat a cast iron skillet over high heat. Slice the onion paper-thin with a mandoline. Divide the beef into 4 balls and season lightly with salt and pepper.
- Place a beef ball on the hot skillet, pile with onions, and smash firmly to 1/4 inch thick. Season with salt and pepper and cook undisturbed for 3 minutes until edges are deeply brown.
- Scrape under the patty and flip so the onions are underneath. Lay a slice of cheese on top and cook 2 to 3 minutes more until the cheese melts and onions are dark and crispy.
- Butter the cut sides of the buns and toast in the skillet until golden, about 1 minute. Place the patty on the bun, add pickles if using, and serve hot.
Notes
Cook in batches if your skillet cannot fit all 4 patties at once, and keep the first burgers warm in a 250°F (120°C) oven while you finish the rest. The onions will soften any leftover patties, so re-crisp them in a hot pan.
