Season the ground beef with salt and pepper. Press the beef mixture onto the tortillas in a thin layer.
Preheat a skillet over medium-high heat. Add half the olive oil and place one tortilla, beef side down, in the skillet. Smash it using the bottom of a saucepan. Cook for 3 minutes.
Flip the tortilla and sprinkle the shredded mozzarella cheese over the beef. Cover the skillet and cook for 2 more minutes. Remove from the pan and repeat with the remaining olive oil and the other tortilla.
To make the sauce, combine the mayonnaise, ketchup, and chopped pickles in a small bowl. Season with pepper.
Assemble your smash burger tacos. Top with lettuce, chopped tomatoes, and burger sauce. Serve warm.