Prep the air fryer: Preheat to 390°F (200°C) for 4–5 minutes. Line the basket with a perforated parchment sheet if you have it, or lightly spray the basket.
Mix the base: In a bowl, whisk the egg, mayonnaise, Dijon, lemon juice, and zest until smooth.
Add flavor and binders: Stir in onion, parsley, garlic, paprika, red pepper flakes, a pinch of salt, and a few grinds of pepper.
Fold in tuna and crumbs: Add the drained tuna, breaking it up with a fork.
Sprinkle in the breadcrumbs and gently mix until the mixture holds together. It should be moist but not wet. If too loose, add 1–2 more tablespoons breadcrumbs.
Form patties: Divide into 6 equal portions.
Shape into patties about 1/2 inch thick. Press the edges so they’re compact and even.
Oil lightly: Spray both sides of each patty with cooking spray. This helps with browning.
Air fry: Arrange patties in a single layer in the basket without touching.
Cook for 8–10 minutes, flipping halfway, until golden and crisp. Thicker patties may need an extra 1–2 minutes.
Serve: Squeeze with fresh lemon and serve hot with your favorite dip—tartar sauce, garlic yogurt, or a spicy mayo all work well.