Preheat your griddle or skillet. Heat your cooking surface over medium-high heat. You want it hot enough to sear the beef quickly.
Make the sauce. In a small bowl, combine mayonnaise, mustard, paprika, vinegar, and Swerve. Stir until well mixed. Set aside.
Prepare toppings. Chop, slice, and set them aside. These will be used to top your tacos.
Shape and cook the burgers. Divide the ground beef into 8 equal portions. Place a ball of beef on the hot griddle. Smash it flat with a heavy spatula or burger press, seasoning with salt and pepper. Let it cook for about 2-3 minutes until the edges are crispy. Flip the burger, immediately top with some shredded cheese, and cook for another minute until the cheese melts.
Warm the tortillas. Briefly heat the tortillas on the griddle, about 30 seconds per side, to make them pliable and slightly toasted.
Assemble the tortilla burgers. Place a cheesy smash burger on each tortilla. Top with onions and pickles. Drizzle with the prepared sauce.
Serve immediately. Enjoy your smash burger tacos hot, complemented by your favorite sides or burger toppings.