How to fillet a flat fish: quarter cut
1. Hold on to the head end of the fish. Starting just behind the small pectoral fin, cut right through the fish outwards following one side of the head. Repeat on the other side. Remove the head.
2. Use scissors to trim off the large fins either side.
3. Use a filleting knife to make a deep cut down the centre line of the fish, through to the backbone but no further.
4. Hold your knife at an angle, insert the knife blade and stroke it down the line of the backbone towards the tail to free the fillet from one side.
5. Turn the fish so that the head is towards you and repeat on the other side.
6. Turn the fish over and repeat. Trim the small side bones from the fillets and remove any roe.