Smash Burger Quesadillas

For the Special Sauce - For the Special Sauce: In a small bowl, stir together mayonnaise, ketchup, pickles or relish, sugar, and vinegar. Set aside or refrigerate if using later.

For the Quesadillas - For the Quesadillas: Portion the ground beef into four 5-ounce balls, pressing together just until the meat holds its shape without falling apart.

For the Quesadillas - Add oil to a 12-inch stainless-steel, carbon steel, or cast iron skillet and heat until smoking. Add one of the meatballs to the skillet and, using a wide, stiff metal spatula, press down on it until it is roughly the diameter of the tortilla. It helps to use something hefty (like a second stiff spatula, tongs, or other sturdy tool) to apply pressure on the spatula to get a good smash. Season with salt and pepper.

For the Quesadillas - Cook undisturbed until a dark brown crust forms, about 2-3 minutes. Carefully flip the patty over, using the edge of the spatula to scrape up all the browned bits.

For the Quesadillas - Top patty with 2 cheese slices and cook for 30 seconds, then add 5-6 pickles and 1-2 tablespoons of onion. Add a tortilla and press down firmly using the spatula to make sure the cheese adheres.

For the Quesadillas - Using your spatula, flip the patty over again, adding 2 more slices of cheese, and place the second tortilla on top. Press to adhere. Flip once more and cook briefly to allow the extra cheese to melt, about 30 seconds. Remove from the pan and repeat the process with the remaining balls of meat, tortillas, and toppings.

For the Quesadillas - Slice each quesadilla into 6 equal triangles. Top with shredded lettuce, if using, and drizzle with special sauce or serve it on the side for dipping.