Method
Preheat oven to 200ºC or gas mark 6
Prepare the mashed potato topping: peel the potatoes, cut into large pieces and boil for 15 minutes or until tender
While the potatoes are cooking make the sauce: melt the butter in a saucepan. Add the flour and mix to form a paste. Gradually add the milk, stirring constantly with a whisk. The sauce will become thick. Reduce the heat, and allow to simmer for 2 minutes. Add the parsley
Place the fish in the sauce and simmer until cooked, 8 – 10 minutes.
Drain the potatoes and add the butter and milk. Mash until smooth and creamy.
Place the fish, sauce and tomatoes into a baking dish. Spoon the mashed potato over the sauce, and bake for 20 minutes in the oven, until golden brown.
Serve with a selection of seasonal vegetables.