Make the burger sauce by mixing the mayo and ketchup in a small bowl. Add a small drizzle of water and stir until the sauce reaches a pourable consistency. Set aside.

Divide the ground beef evenly among the tortillas. Press the beef into a thin, even layer, spreading it almost to the edges of each tortilla. Season lightly with salt.

Heat a skillet over high heat and spray with cooking spray. Place a tortilla in the skillet meat-side down and cook for 3-5 minutes, until the beef is well browned and cooked through.

Carefully flip the tortilla using a spatula. Reduce the heat to medium. Place a slice of cheese on top of the beef, cover the skillet with a lid, and cook for 1-3 more minutes, until the cheese is melted.

Transfer to a plate and top with shredded lettuce, pickles, and the prepared burger sauce. Add any additional low-calorie toppings you like (onion, tomato, mustard, relish, etc).