In a small bowl, whisk together the mayonnaise, ketchup, sweet relish, and yellow mustard to create the special burger sauce. Set aside.

Divide the ground beef into 8 equal portions and roll them into loose balls. Place one beef ball onto a flour tortilla and use your hands to smash and spread it into a thin, even layer covering the entire tortilla.

Season the raw beef layer with salt and pepper.

Heat a large skillet or griddle over medium-high heat. Place the tortilla meat-side down onto the hot pan.

Press down firmly with a spatula and cook for 3-4 minutes until the beef is browned and crispy.

Flip the tortilla (meat side up), place a slice of American cheese on the hot beef, and let it melt for 1 minute while the bottom of the tortilla gets slightly crispy.

Remove from the pan. Top with the special sauce, shredded lettuce, diced onions, and chopped pickles. Fold like a taco and eat immediately!