When fish fillets are cooked, the thin membrane on the skinned side may shrink and cause them to buckle. To prevent this they are often flattened and scored. Here, a sole fillet is shown.
Place the fillet between two sheets of plastic wrap and pound it lightly with the flat side of a large knife blade.
With the tip of a knife, score the fillets lightly in parallel slanting lines on the side that has been skinned.