Make the Sauce: In a small mixing bowl, whisk together the mayonnaise, ketchup, yellow mustard, sweet pickle relish, garlic powder, and onion powder until smooth. Keep in the refrigerator until ready to use.

Prep the Meat: Divide the pound of ground beef into 8 equal portions, rolling each one into a loose ball (about 2 ounces each).

Smash the Tacos: Place one small flour tortilla flat on your work surface. Place one meatball in the center of the tortilla. Using your hands, press the meat down firmly, spreading it out into a very thin, even layer that reaches all the way to the edges of the tortilla. Season the raw meat evenly with a pinch of salt and pepper. Repeat with the remaining tortillas and meat.

Sear the Beef: Heat a large cast-iron skillet or griddle over medium-high heat. Add a tiny drizzle of vegetable oil. Once hot, place the prepared tortilla directly into the pan, meat-side down.

Cook and Flip: Use a heavy spatula to press down firmly on the back of the tortilla to ensure maximum contact with the pan. Cook for 2 to 3 minutes until the beef is browned and crispy. Flip the taco over so the tortilla side is now touching the pan.

Melt the Cheese: Immediately place a slice of cheese over the hot beef. Let it cook for 1 more minute until the bottom of the tortilla is lightly toasted and the cheese is completely melted. Remove from the pan and transfer to a serving plate. Repeat the cooking process with the remaining tacos.

Assemble and Serve: Top each cheesy taco with shredded iceberg lettuce, diced onions, and sliced pickles. Drizzle generously with the prepared burger sauce. Fold in half and enjoy immediately!