In a mixing bowl, combine extra lean ground beef, egg, breadcrumbs, cumin, salt, and pepper. Mix until evenly combined.

Divide the meat mixture into 10 equal portions and roll into balls.

Take a flour tortilla, lay it flat, place one meatball in the center and press down into a thin layer.

Heat a skillet over medium heat, place the tortilla with meat side down, and cook for 3-4 minutes.

Flip the taco, place two slices of cheese on top, cover, and cook for another 1-2 minutes until cheese melts.

Remove from skillet and add toppings: lettuce, onion, pickles, and Big Mac sauce.

Keep cooked tacos warm in a preheated oven at 175°F while finishing the rest.