In a small mixing bowl, whisk together the ⅓ cup mayonnaise, 2 tbsp ketchup, 1 tbsp yellow mustard, 2 tbsp dill pickle relish, and ½ tsp white vinegar until smooth. Taste and adjust seasoning if needed. Refrigerate until ready to serve.

Divide the 1 lb ground beef 80/20 fat ratio for best flavor and crispiness into 4 equal balls (about 4 oz each). Season each ball generously with 1 tsp garlic powder, 1 tsp onion powder, ¾ tsp kosher salt, and ½ tsp black pepper on all sides. Do not overwork the meat — keep the balls loose.

Heat a large cast iron skillet over high heat until it is very hot and just beginning to smoke. Place one 4 pieces small flour tortillas flat in the pan, then immediately place a 1 lb ground beef 80/20 fat ratio for best flavor and crispiness ball in the center of the tortilla. Using a sturdy spatula or the bottom of a heavy pan, press and smash the 1 lb ground beef 80/20 fat ratio for best flavor and crispiness ball firmly and evenly across the tortilla until it covers most of the surface. Cook for 2–3 minutes until the edges are deeply browned and crispy.

Flip 4 pieces small flour tortillas together in one motion. Immediately lay a slice of American cheese on top of the ground beef 80/20 fat ratio for best flavor and crispiness. Cook for another 1–2 minutes until the cheese is fully melted and the tortilla is lightly golden and slightly crisp on the bottom. Transfer to a plate and repeat with remaining ground beef 80/20 fat ratio for best flavor and crispiness balls and 4 pieces small flour tortillas.

Spread a generous spoonful of mayonnaise over the melted cheese side of each smash burger taco. Top with a handful of shredded 1 cup shredded iceberg lettuce, a few dill pickle chips or sliced dill pickles, and diced small white onion if using. Fold the taco in half like a traditional taco and serve immediately while hot and crispy.