Remove the fillets from the fridge 10 minutes before cooking. Pat every surface completely dry.

Score the skin of each fillet with two shallow diagonal cuts, about 1 cm deep, to stop it curling.

Rub the flesh side with smoked paprika, half the salt and the black pepper. Leave the skin side unseasoned for now.

Heat a cast-iron skillet over medium-high for 3 minutes until it just starts to smoke lightly. Add 2 tbsp oil and swirl to coat.

Season the skin side with the remaining salt just before laying the fillets skin-side down.

Press each fillet gently with a fish spatula for the first 10 seconds to keep the skin flat.

Cook skin-side down 4 to 5 minutes without moving, until the skin is golden and crisp and the flesh is opaque about two-thirds up the sides.

Flip and cook flesh-side down 60 to 90 seconds until just cooked through. The center should be barely opaque with a hint of pink.

Transfer to a wire rack and rest 2 minutes.

Reduce heat to medium. Add the remaining 1 tbsp oil to the same pan.

Add the sliced garlic and cook 60 seconds, stirring, until golden and fragrant but not brown.

Add the lemon zest and juice carefully (it will spit). Stir and cook 30 seconds until slightly reduced.

Add chili flakes if using, then spoon the sauce over the rested fillets.

Scatter parsley over the top and serve immediately.