Take ground beef out of the fridge 15 minutes before cooking — cold meat hits a hot pan and the outside overcooks before the inside catches up.
Divide into 4 equal portions. Handle as little as possible — overworking ground beef makes tough burgers.
Form into patties slightly wider than your buns (they shrink as they cook). Make a small dimple in the center of each — this prevents them from puffing up.
Season ONLY the outside generously with salt right before cooking. Never mix salt into the meat.
Heat a cast-iron skillet or grill to very high heat. Add a thin film of oil.
Cook patties 3–4 minutes per side for medium. Do not press down — you're squeezing out the juices.
Place cheddar on top in the last 1 minute and cover to melt.
Rest 2 minutes before serving. Use this time to toast the buns.