Divide the hamburger meat between the tortillas evenly. Top the hamburger meat with salt and pepper. Then smash some diced onion on top. You will lose about half of them.
In a large skillet, or preferably a large griddle, place your prepared tortillas meat side down. I sprayed my pan but I didn't need to. Smash and cook.
While cooking, make the big mac sauce. Combine all of the sauce ingredients in small bowl, stir.
Continue to cook the smash burger/tacos. I flipped a few times, making sure the tortillas weren't soggy (you might not have to worry about that at all).
Once cooked, remove to a plate and top with the cheese.
Place the other tortillas meat side down and keep cooking.
Top with cheese with lettuce, onions, dill relish or pickles, sauce, and sesame seeds. If you have extra sauce, add some to each plate.
