To make the sauce: Mix all ingredients together in a bowl or jug.
To each tortilla, add about 1/4 cup of beef mince and flatten out to completely cover the surface to the edges. Add more meat if you prefer a thicker patty. Sprinkle it with salt and pepper on top.
Preheat a large frying pan on high heat. Add 2-3 tacos, mince facing down. Cook for approx. 3-4 minutes, until the mince has browned and cooked through.
Flip over, lower the heat right down (so the tortillas don't burn), add the burger cheese on top of the patties, place a lid on top so that the cheese melts. Let them cook for approx. 2-3 minutes, until the cheese has melted. Remove from the heat.
Top the taco with shredded lettuce, pickles and drizzle over the big mac sauce.