Combine all the ingredientes except fish, onions, mushrooms and prosciutto

Brush worcestershire sauce mixture inside and out the fish.

Stuff the fish with one layer of chopped onions, one of laminated mushrooms and one slice of prosciutto.

Place fish in a baking pan with the remaining onions and mushrooms.

Bake in a preheated oven at 200° C for 10 minutes.

Turn the fish over after 10 minutes and baste it with pan juices.