Preheat the oven to gas 4 / 180C / 350°F. Grease 4 squares of tin foil big enough to wrap your fish fillets in a parcel with butter so the fillets won't stick to it
Lay a fillet in the middle of each piece of buttered foil, season with salt & pepper and a squeeze of lemon juice and fold the foil like an envelope around the fish
Place the wrapped fillets on an oven tray and bake for 16 - 20 minutes. They should be a uniform colour throughout and starting to flake
In the meantime cook some vegetables to serve alongside such as broccoli, potatoes, carrot, cabbage etc and start the sauce
In a pan melt the dairy-free spread, stir in the cornstarch then gradually add the milk stirring constantly until it thickens
Season with salt and pepper, stir in the parsley then serve poured over the fillets
