Form meat into eight patties on a piece of parchment paper then cut a square around each patty, this helps place the patty into the hot skillet. You want the patties thin and slightly larger than the size of your bun. Sprinkle with salt and pepper. Let come to room temperature for about 15 minutes.

Meanwhile mix the mayonnaise, ketchup, and relish in a small bowl

Preheat a cast-iron skillet on medium-high heat add 1/2 teaspoon oil and place your buns split side down in the heated pan, cook until toasted about 1 minute. Set aside and cover to keep warm.

Pick up a patty and place the salt and pepper side down into the hot skillet, then pull off the parchment paper. Cook without moving until well browned and crusty on the first side, about 2½ minutes. While they are cooking, spread 2 teaspoons of mustard on the raw side. Then flip and top each side with 2 slices of cheese continue cooking for 1 more minute.

Spread sauce on the bottom toasted bun, place tomato, onion, and lettuce then patty with melted cheese add the top bun and serve.