In a medium bowl, whisk together mayo, sweet pickle relish, mustard, vinegar, paprika, onion powder, garlic powder, and white pepper. Refrigerate for at least 20-30 minutes.

Heat a skillet over medium heat. Cook flour tortillas for 1-2 minutes on each side until lightly charred. Keep warm under a clean towel.

Divide ground beef into 4 equal balls. Heat cast iron skillet over medium-high heat until very hot.

Place a beef ball on the skillet and press down firmly with a spatula using parchment paper. Smash thin to about 1/4 inch thick.

Sprinkle with salt and pepper. Cook for 2-3 minutes, flip, and top with cheese. Cook another 1-2 minutes until edges are crispy and cheese melts.

Spread Big Mac sauce on each tortilla. Add lettuce, onion, and pickles.

Place a cheesy patty on each tortilla and fold like a taco. Serve warm with extra sauce.