Rehydrate the onions: Combine 2 tablespoons dried minced onion with 3 tablespoons warm water (for onions) in a small bowl. Let sit until soft and plumped. This is McDonald's biggest secret — they use dehydrated minced onions, not fresh, which gives that signature drive-thru flavor.
Portion the beef: Divide 1 pounds ground beef (80/20 chuck) into 4 equal balls (about 4 oz each). Do not season yet and do not pack tightly — loose, gently formed meatballs smash flatter and crispier.
Heat the griddle: Heat a cast iron skillet or flat-top griddle over medium-high heat until ripping hot. Add 1 tablespoons neutral oil (for griddle) and swirl to coat the surface evenly.
Toast the buns: Split 4 soft hamburger buns and place cut-side down on the hot griddle. Toast until lightly golden and lightly crisp. Remove and set aside.
Smash the patties: Place the beef balls on the hot griddle. Immediately smash each one flat with a sturdy spatula or burger press until paper-thin (about 1/4 inch). Press hard to maximize contact with the griddle and create those iconic crispy lacy edges.
Season and sear: Sprinkle the smashed patties with 1 teaspoons salt and 0.5 teaspoons black pepper. Cook undisturbed until a deep brown crust forms on the bottom — do not move them or you'll lose the crust.
Flip and add cheese: Flip each patty, making sure to scrape up all the crispy browned bits with the spatula. Immediately top each patty with a slice of 4 American cheese slices. Cook until the cheese is fully melted and draped over the edges.
Build the burger: On each toasted bottom bun, spread 4 teaspoons ketchup and 2 teaspoons yellow mustard. Add 2 slices from your 8 dill pickle slices, then a small sprinkle of the rehydrated onions, then the cheesy smashed patty. Cap with the top bun.
Steam and serve: Wrap each finished burger tightly in parchment paper or foil and let rest. This steams the bun and melds the flavors together — exactly like McDonald's does before handing them out at the drive-thru window. Optional but highly recommended for authenticity.