Make the sauce (optional): In a small bowl, mix mayo, ketchup, mustard, pickle brine, sugar, and paprika.
Taste and adjust. Set aside.
Cook the beef: Heat a skillet over medium-high. Add ground beef and break it up.
When it starts to brown, stir in onion and a pinch of salt. Cook until the beef is no longer pink and onions are soft, about 5–7 minutes. Stir in garlic (if using) during the last minute.
Season well: Sprinkle in salt, pepper, smoked paprika, and garlic powder.
Cook 1 more minute to bloom the spices. Drain excess fat if needed so the quesadilla doesn’t get greasy.
Preheat the air fryer: Set to 375°F (190°C) for 3–5 minutes. Lightly spray the basket or tray.
Assemble the quesadilla: Lay a tortilla on a board.
Spread a thin layer of ketchup and mustard, or a swipe of burger sauce. Sprinkle a layer of cheese over half the tortilla, add a generous spoonful of beef, scatter chopped pickles, then another light layer of cheese. Fold the tortilla over to make a half-moon.
Press gently so it seals.
Light oil mist: Spray the outside of the tortilla lightly with oil. This helps it turn golden and crisp.
Air fry: Place the folded quesadilla in the basket. Cook 4–6 minutes, flipping halfway, until the tortilla is crisp and the cheese is melted.
Timing varies by air fryer and tortilla size—peek at 4 minutes.
Repeat: Assemble and cook remaining quesadillas. Don’t crowd the basket; cook in batches for best results.
Finish and serve: Let rest 1 minute before slicing so the cheese sets. Serve with extra sauce for dipping.
Add shredded lettuce or tomato on the side if you like a “fresh” bite with each piece.