1: Bring the fish to room temperature. Using a sharp knife, cut a few shallow incisions into the skin of each fillet to help prevent it curling up during cooking. Don’t cut too deeply – you only want to cut into the skin, not the flesh.

2: To make the Cajun rub, mix all the ingredients together in a bowl until evenly combined.

3: Brush the fish fillets with the melted butter to coat them all over then lay on a baking tray. Sprinkle over about 3 tbsp of the Cajun rub, gently patting it onto the fillets and making sure they’re evenly covered on both sides. Gently shake off any excess.

4: You will need to cook the fish fillets in batches, to avoid overcrowding the pan. Heat a large, cast-iron skillet or heavy-based frying pan over a high heat until it’s smoking hot.

5: Place a couple of fillets skin side down in the pan. Carefully hold them down by pressing with a fish slice or spatula until they have relaxed and no longer want to curl up. Cook until the skin is very well browned – almost black but not burnt! Depending how hot your pan is, this should take 3–4 minutes. You want the fish to be 90 per cent cooked through.

6: Carefully flip the fillets over with a fish slice and cook the other side for about 2 minutes until crisp. Remove to a plate and keep warm while you cook the rest of the fillets. Serve the fillets as soon as they are all cooked, on warmed plates.