1. Mix together the butter, herbs and zest. Use most of this butter mixture to sandwich together the two pieces of fish. Season with salt and freshly ground black pepper.
2. Wrap the fish with rashers of the Parma ham, holding the fillets together firmly as you do. Hold the ham in place by tying the fish parcel firmly with pieces of string - you will need about 6 pieces. Rub the surface with the rest of the butter mixture and refrigerate until ready to cook.
zest