01 -
In a bowl, whisk together mayonnaise, ketchup, yellow mustard, sugar, vinegar, smoked paprika, onion powder, salt, pepper, and Worcestershire sauce until smooth and creamy. Refrigerate to allow flavors to meld.
02 -
Heat a large skillet over medium heat. Add ground beef and chopped onion, breaking meat apart. Cook until beef is no longer pink and onions are softened. Drain excess fat. Season with salt, pepper, and garlic powder, stirring well.
03 -
Stir in relish, ketchup, yellow mustard, and Worcestershire sauce into the beef mixture. Let simmer for 1 minute to combine flavors. Remove from heat and allow to cool slightly to prevent cheese from melting prematurely.
04 -
Place half of the tortillas on a flat surface. On each tortilla, layer 2 to 3 slices of American cheese, evenly spread a portion of the cooled beef mixture, then add 1 to 2 more slices of cheese. Top with remaining tortillas to form sandwiches.
05 -
Heat a large, lightly oiled skillet over medium-high heat. Place one assembled quesadilla in the skillet and cook for 2 to 3 minutes per side until the tortilla is golden and cheese is melted. Repeat with remaining quesadillas.
06 -
Transfer quesadillas to a cutting board and slice each into quarters while still hot. Serve immediately alongside the prepared dipping sauce.