Place the frozen burgers in the air fryer basket. Spray them lightly with oil on both sides.
Turn on the machine (no preheating).
Cook the frozen patties at 360°F (180°C) for 5 minutes.
Season them with salt and pepper, flip and season the other side.
Cook the patties for another 3 to 5 minutes, depending on their thickness (Note 2).
Cover them with a slice of cheese and cook for another minute until the cheese melts.
Remove from the basket with a spatula and let rest while you warm the buns.
Split the buns in half, place them in the basket and warm them for about 2 minutes.
Build the burgers:
Smear the lower slice of the bun with ketchup and the other one with mayonnaise.
Place the patty with the melted cheese on the lower bun half.
Add onion, tomato slices, and the salad leaf.
Cover with the upper bun slice. Serve immediately.
1. I’ve tried many brands; they all work great. Their thickness might vary; adjust the cooking time accordingly.2. Approximate cooking times:¼ lb (100 g): 8 to 10 minutes, flip after 5 minutes. Add 1 minute for the cheese.1/3 lb (150 g): 12 to 15 minutes, flip after 7 minutes. Add 1 minute for the cheese.3. Cheddar, Swiss, Gouda, etc.4. Or another sauce you like: hot sauce, sweet and sour sauce, sriracha, buffalo sauce, etc.