Nigel Slater's fish dishes

I do love a fish pie with its flaky, undulating pastry crust or deep furrowed lid of mashed potatoes crisped in the oven. For an everyday fish pie, I take a shortcut with the crust using breadcrumbs and herbs blitzed in the food processor. That way I get a crisp lid to contrast with the softness underneath without having to make and roll pastry or peel a spud. When time is of less importance, I use a more traditional crust of butter and flour or potatoes whipped up with parsley and butter.

Which fish I use for a pie will change according to supply, whim and conscience. Fish is rarely a cheap eat, but we can trim the bill a little by choosing the less popular varieties, such as ling and whiting and, if it is to our taste, coley. A sustainable alternative to the knee-jerk varieties is crucial, and I have had much success with using pollack and line-caught haddock, too. A handful of shellfish, be it in the form of clams, prawns or a mussel or two, will lend much in terms of flavour, but is far from essential. I am not sure anything good will come from adding too many bits and bobs.

If there is one recipe that responds to a handful of fresh herbs it is that of a fish-pie filling. Parsley feels crucial, but I like to include dill, too, and sometimes even lemon thyme. The tougher herbs – rosemary and common thyme – belong on the grill with a nice bit of sea bass.

But it's the crust rather than the filling I have been working on of late; whizzing up good, firm bread with fresh herbs and other seasonings in the food processor – a job of seconds rather than minutes. I introduced dried oregano with a bit of success and another time some dried herbes de provence gave a pleasingly French note to the salmon and haddock beneath. (An attempt at a crumb crust flecked with ground spices felt like my fish was in the hands of the school bully.) Best of all the breadcrumb toppings I tried was one involving anchovies, lemon zest and parsley. It had just the right level of crunch and savour and was on top of the green-flecked sauce quicker than you could say Findus.

HADDOCK AND DILL CRUMB CRUST PIE

Check the Marine Conservation Society's website (fishonline.org) for advice on which sustainable seafood to buy. I used line-caught haddock and salmon with mussels.

Serves 4
For the filling:
assorted fish (see above) 750g
milk 500ml
bay leaves a couple
mussels 750g
white wine or water 1 small glass
spring onions a bunch
butter a thick slice
button mushrooms 400g
dill 6 stems
plain flour 2 tbsp

For the crust:
white bread 400g
anchovy fillets 8
parsley 4 or 5 bushy sprigs
lemon zest finely grated, 2 tsp
olive oil 4 tbsp

DIRECTIONS

Check the fish carefully for bones or skin, cutting it into large chunks as you go, then place in a saucepan over a moderate heat with the milk, bay leaves, a little salt and black pepper. As it approaches the boil, lower the heat so that the milk bubbles lazily around the fish, rather than boiling fiercely. Leave it to cook for 7-10 minutes, until its flesh is opaque, then set aside.

Scrub the mussels, pulling away any beards trapped between the shells, and knocking off barnacles with the back of a kitchen knife. Check carefully that none have cracked or broken shells. Pile them in a pan, pour over the white wine or water and bring to the boil. As soon as the mussels start to open, a matter of seconds, remove them from the pan and set aside.

Lift the cooked fish out of its cooking liquid with a draining spoon and transfer to a baking dish. Reserve the liquid from the cooked fish. Remove the mussels from their shells, discarding the cooking liquid, and add to the fish, removing the bay leaf.

Chop the spring onions. Rinse the mussel pan, melt the butter in it over a moderate heat, then add the spring onions. While they soften, slice the mushrooms and add them to the pan, stirring until they are coated in butter. Cover with a lid and cook for 5 minutes. Chop the dill and stir into the mushrooms with a generous grinding of salt and black pepper. Stir in the flour.

Warm the reserved fish cooking liquid (there should be about 500ml) in a saucepan then pour into the mushrooms, stirring until there are no lumps of flour left. Bring to the boil, then turn down the heat and cook, with the occasional stir, for 5 minutes. Gently fold in the fish and mussels. Tip into a baking dish or roasting tin and set aside. Heat the oven to 200C/gas mark 6.

To make the crust, blitz the bread in a food processor. Add the chopped anchovies and parsley. Stir in the lemon zest and a little salt then scatter over the fish. Trickle the olive oil over it and bake for 30-35 minutes, until the crumbs have a golden crust.

SALMON WITH LEEKS AND CREAM

Any firm fish would be suitable, but the salmon seems to appreciate being in the same recipe as leeks. If 50ml of cream seems like too little, then do add more.

Serves 2
leeks 4, medium-sized
butter a thick slice, about 40g
broccoli 350g
plain flour 2 tbsp
fish or vegetable stock 250ml
double cream 50ml
tarragon or dill 4 or 5 bushy sprigs

DIRECTIONS

Slice the leeks into thick coins, put them in a colander and wash them. Shake dry and tip into a deep saucepan with the butter. Cook for 15 minutes or so, stirring occasionally and cover with a lid. Break the broccoli into large florets, then steam or boil for a few minutes until tender. Stir the flour into the leeks, followed by the stock, simmering gently for 10 minutes or so and stirring regularly. Lower the fish into the pan with the leeks, spooning over some of the sauce. Season carefully, then chop the dill or tarragon and stir in the cream and then broccoli. Leave over a low heat for 7 minutes or so, until the fish is just cooked, then serve.

Email Nigel at nigel.slater@observer.co.uk or visit theguardian.com/profile/nigelslater for all his recipes in one place