Lightly oil a sheet of aluminium foil and place thin slices of lemon and onion to form a layer sufficient to rest the fish pieces on. Place more onion slices on top of the fish and a bay leaf or two. Dice two tomatoes and spoon around the fish pieces. Sprinkle with salt and pepper and a little more oil. Close the foil to form an air-tight parcel and put the whole lot in a frying pan with a small amount of oil.

Cover and cook over medium heat for five minutes.

Remove from heat and transfer the fish to warmed plates.

Return the tomatoes and onions to the pan and reduce to make a sauce, season to taste with sugar, salt and pepper.

Serve with boiled potatoes and mushy peas.