Preheat the air fryer: Set it to 390°F (200°C) and let it heat for 3–5 minutes. Lightly spray the basket with olive oil.
Mix the base: In a medium bowl, combine drained tuna, Parmesan, breadcrumbs, egg, mayonnaise, and Dijon.
Break up the tuna with a fork so it mixes evenly.
Add flavor: Stir in onion, celery, garlic, parsley, lemon zest, lemon juice, paprika, and red pepper flakes. Season with salt and pepper. The mixture should be moist but hold together when pressed.
Adjust texture: If the mix is too wet, add a tablespoon of breadcrumbs at a time.
If too dry, add a teaspoon of mayo or lemon juice.
Form patties: Divide the mixture into 6–8 small patties (about 2–3 inches wide, 1/2-inch thick). Press firmly so they don’t crumble.
Oil lightly: Spray the tops with olive oil. This helps the crust brown beautifully.
Air fry the first side: Arrange patties in a single layer in the basket without crowding.
Cook for 7–8 minutes.
Flip and finish: Carefully flip, spray again, and cook 4–6 more minutes, until golden brown and crisp. Internal temp should reach at least 145°F (63°C).
Serve: Squeeze with lemon and serve hot with your favorite dip—tartar sauce, garlic yogurt, or a quick lemon aioli.