1. Scale the fish and then remove the head by cutting diagonally just behind the gills on both sides from under the pelvic fin around to the top of the head. This will retain all the fillet. 

2. Starting at the head end, cut through the skin slightly to one side of the backbone along the whole length of the fish, using a sharp, thin-bladed, flexible knife. 

3. Return to the head end and gradually cut the fillet away from the bones, keeping the blade as close to the bones as you can. When you reach the ribcage, if the bones are thick, continue to cut close to them until the fillet comes free. However, if the bones are fine, cut through them and remove them from the fillet with fish pliers or tweezers afterwards. 

4. As you near the tail end, get the whole blade of the knife under the fillet, rest the other hand on top of the fish and cut the remainder away in one clean sweep. Turn the fish over and repeat on the other side. 

5. Remove any bones from the fillets with fish pliers or tweezers. 

6. Trim up the edges of each fillet and cut away the thinnest part of the belly flap. Cut the fillet across into portion-sized pieces weighing around 200g.