Fish and leek bake

Method

1. Preheat the oven to 200°C/fan180°C/gas 6.
2. Heat the olive oil in a saucepan over a low heat. Add the leek and cook gently for 10 minutes until very soft. Stir in the watercress sauce and Dijon mustard. Raise the heat to bring just to the boil, then remove from the heat.
3. Mix together the grated cheese and breadcrumbs, then season with black pepper.
4. Arrange the fish fillets in a shallow ovenproof baking dish. Pour over the sauce and sprinkle over the cheesy crumb mixture. Bake in the oven for 10-15 minutes until the fish is just cooked through. Serve with mash and green veg, if you like.