Smash Burgers

Ingredients

• 1½ lb ground chuck, 80/20, kept cold
• 1½ tsp Diamond Crystal kosher salt
• ½ tsp black pepper, freshly ground
• 8 slices American cheese
• 4 potato buns, split
• 2 tbsp butter, softened

For the sauce

• ¼ cup mayonnaise
• 2 tbsp ketchup
• 1 tsp yellow mustard

For serving

• ½ cup dill pickle chips
• ½ small white onion, sliced paper thin

The salt amounts here are for Diamond Crystal kosher salt. If you have Morton kosher salt, use a little over half as much, because its grains are denser and saltier by the spoon.

Steps

1. Divide the beef into 8 balls, two per burger, about 3 ounces each. Roll them loosely, just enough to hold together; packed meat smashes into a dense patty. Set them on a plate and refrigerate for at least 15 minutes while you get everything else ready. Cut a square of parchment about 6 inches wide.
2. Stir together the mayonnaise, ketchup and mustard. Have the pickles, onion and cheese next to the stove, along with a stiff metal spatula and something heavy to press it with, like a second spatula or a small saucepan.
3. Open a window and heat a 12-inch cast-iron or carbon steel skillet over medium heat for 5 minutes. Spread the butter on the cut sides of the buns and toast them, cut side down, until golden, about 1 minute per batch. Set them aside, wipe the pan with a paper towel, and turn the heat to high for 2 more minutes, until the pan is smoking.
4. Put one ball of beef in the pan, lay the parchment on it, set the spatula on top, and lean on it with the saucepan or second spatula until the patty is thinner than 1/4 inch with ragged edges. Do it right away; once the meat starts to cook it stops spreading. Peel off the parchment and repeat with a second ball, well apart from the first. Season the tops with salt and pepper.
5. Leave the patties alone until the edges are dark brown and lacy and the tops have turned grey around the rims, 1 1/2 to 2 minutes. Push the edge of the spatula hard against the pan and scrape under each patty, then flip. Lay a slice of cheese on each and cook until it slumps, about 30 seconds. These patties are too thin for a thermometer, so break the first one open: it should have no pink left in the middle. Stack one patty on the other on a bottom bun, add pickles and onion, spread sauce on a top bun, and serve the burger while you cook the next.
6. Scrape any stuck bits out of the pan and repeat with the remaining beef, two balls at a time, salting and peppering each batch and serving each burger as soon as it's built.

Notes

Patties this thin always cook through to well done, which is what the USDA asks for in ground beef (160°F), so if you like a pink middle, make a thick burger instead. Use 80/20 chuck, nothing leaner, or the patties dry out before they brown. The balls can be shaped up to a day ahead and kept covered in the fridge. Expect smoke; a carbon steel or cast-iron pan is the right tool, and nonstick shouldn't go this hot.