J. Kenji López-alt's Classic Smash Burgers

Prepare the special sauce: In a small bowl, combine 1/4 cup mayonnaise, 2 tablespoons ketchup, 1 tablespoon yellow mustard, 1 tablespoon sweet pickle relish, and 1/2 teaspoon hot sauce (if using). Stir well and set aside.

Prepare ingredients: Divide 1 pound of ground beef into 4 equal, loose balls. Thinly slice 1/4 of a yellow onion and set aside with 1/2 cup dill pickle slices.

Toast the buns: Heat a large cast iron skillet or griddle over medium heat. Add 2 tablespoons of unsalted butter and melt. Place the cut sides of the 4 potato buns onto the buttered surface and toast until golden brown, about 1-2 minutes. Remove and set aside.

Heat the griddle: Increase the heat to high. The skillet should be smoking hot.

Smash the patties: Place the 4 beef balls onto the hot skillet, leaving space between them. Immediately season each ball with a pinch of 1/2 teaspoon kosher salt and 1/4 teaspoon freshly ground black pepper. Using a sturdy metal spatula and a second spatula or press, firmly smash each beef ball into a very thin patty, about 1/4-inch thick.

Cook the patties: Cook the patties undisturbed for 90 seconds, or until a deep brown crust forms. Use the spatula to scrape under the patty, ensuring all the crust comes with it, and flip.

Add cheese and finish: Immediately place 1 slice of American cheese on top of each flipped patty. Continue to cook for another 60 seconds, or until the cheese is melted and the patties are cooked through.

Assemble the burgers: Transfer the cooked patties to the toasted potato buns. Spread a generous amount of the special sauce on both halves of the bun. Top with sliced yellow onion and dill pickle slices. Serve immediately.