Prepare Special Sauce. Place mayonnaise, ketchup, mustard, dill pickle relish and hot sauce into a small mixing bowl. Stir until well combined. Set aside until ready to garnish tacos.
Season Beef. Season ground beef with salt and pepper in a large mixing bowl. Stir to combine then divide evenly into fourths.
Cook Smashburger Tacos. Place one burger mound into a hot skillet over medium heat. Press flat with a spatula then add a tortilla to the top and continue to press flat as it cooks. This takes 3-4 minutes to brown the beef.
Flip Tacos and Add Cheese. When beef is cooked through flip, add a slice of cheese and cover with lid for a few minutes until cheese is melted.
Add Toppings. Top each taco with lettuce, special sauce and pickles. Serve hot.
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Notes
Use a nice lean ground beef for the tacos. Less fat drippings in the pan while cooking makes it much easier.
If you have flat griddle, that is ideal to cook all of the tacos at one time. I used a hot skillet which works just fine too. Each taco gets cooked separately.
If cooking tacos separately, keep the oven on warm and place the cooked tacos on a baking sheet in a warm oven until they're all done cooking. When ready, garnish all and serve together.