Dry and check the fish. Lay the fillets on kitchen paper and press gently until the surface feels tacky rather than wet. Run your fingertips over each one to check for stray bones — they should feel perfectly smooth. Set the air fryer to preheat at 190°C for 3 minutes.

Build the coating. In a shallow bowl, whisk together the flour, cornflour, lemon pepper, garlic powder, salt, black pepper, dried parsley and lemon zest. It should smell sharply citrusy and peppery the moment you stir it.

Dress the fish. Brush each fillet all over with the olive oil, then press it into the seasoning mixture so every side is evenly coated. The fillets should look pale gold and slightly textured, not caked.

Prepare the basket. Lay two or three lemon slices in the base of the air fryer drawer — they perfume the fish as it cooks and stop it sticking. Place the fillets on top in a single layer, leaving a finger's width between them. If your fillets are large, cook them in two batches rather than crowding them.

Air fry. Cook at 190°C for 8 minutes. At this point the coating should be set and lightly golden at the edges, and you'll hear a gentle sizzle when you open the drawer.

Finish with butter and lemon. Brush the melted butter over the tops and squeeze over the juice of half a lemon. Cook for a further 2–4 minutes, until the fish flakes easily when nudged with a fork and the internal temperature reads 63°C. The butter should smell nutty and the lemon sharp and fresh.

Rest briefly. Lift the fillets onto a warmed plate and leave them for 2 minutes. Scatter with fresh parsley and serve with lemon wedges.