First make the maître d’hôtel butter. Cream the butter, stir in the parsley and a few drops of lemon juice at a time. Roll into butter pats or form into a roll and wrap in greaseproof paper or tinfoil, screwing each end so that it looks like a cracker. Refrigerate to harden.
Heat the grill pan. Dip the fish fillets in flour which has been seasoned with salt and freshly ground pepper. Sh