Ingredients (Serves 4)
Meat: 500g (approx. 1.1 lbs) ground beef (ideally 20% fat content, like chuck, to ensure juiciness).
Buns: 4 burger buns (brioche or potato buns).
Cheese: 4 slices of American cheddar or classic American cheese.
Onions: 1 medium onion, sliced paper-thin (optional).
Seasoning: Salt and freshly ground black pepper to taste.
Butter: 1 tablespoon for toasting the buns.
Secret Burger Sauce:
3 tablespoons mayonnaise.
1 tablespoon ketchup.
1 teaspoon yellow mustard.
1/2 teaspoon garlic powder.
A pinch of finely minced dill pickles.
Step-by-Step Instructions
Prepare the Sauce:
In a small bowl, whisk together the mayonnaise, ketchup, mustard, garlic powder, and minced pickles until smooth. Set aside.
Shape the Meat:
Divide the ground beef into 4 equal balls. Avoid overworking the meat so it stays tender and juicy.
The Smash Technique:
Heat a cast-iron skillet or griddle over high heat until it is screaming hot.
Place the meat balls onto the hot surface, and use a heavy burger press (or a sturdy spatula) to press down firmly until the patty is thin with lacy, crispy edges.
Season the top of each patty with salt and black pepper, and press the thin onion slices directly into the raw top of the meat (optional).
Cook for about 2 minutes until the edges are dark and crispy, then flip.
Add the Cheese:
Place a slice of cheese on top of each patty immediately after flipping. Cover the skillet for about 1 minute until the cheese is completely melted.
Toast the Buns:
Spread a thin layer of butter on the inside of the burger buns and toast them on a hot skillet until golden and crisp.
Assembly:
Spread a generous amount of the secret sauce on both the top and bottom buns.
Place the cheesy patty on the bottom bun, add extra pickle slices or crisp lettuce if desired, and top with the bun.
Pro Tip: The secret to an authentic American smash burger is using high-fat beef and pressing it down hard during the first minute on an extremely hot surface to get that 
signature crispy, juicy crust.