In a small bowl, combine mayonnaise, ketchup, mustard, and sweet pickle relish. Mix well until smooth and set aside in the refrigerator.

In a large skillet over medium-high heat, brown the ground beef, breaking it into small crumbles. Season with garlic powder, onion powder, salt, and black pepper. Cook for 8-10 minutes until fully cooked and no pink remains. Drain excess fat.

If using hard taco shells, warm them in the oven at 350 degrees Fahrenheit for 3-5 minutes. If using soft shells, warm them in a dry skillet for 30 seconds per side.

Start by spreading a generous amount of special sauce inside each taco shell. Add a layer of shredded lettuce as the base.

Spoon the seasoned ground beef over the lettuce. Top with shredded cheddar cheese, diced onions, and diced pickles.

Drizzle additional special sauce over the top of each taco. Serve immediately while warm and enjoy your Big Mac Tacos.