When it’s cold outside, a hearty fish pie is the answer to everything. As with anything of traditional fare, this is the perfect dish to use up whatever’s available – swap the celeriac for traditional, regular potatoes or even sweet potatoes, if you like, or chuck in any leftover bits of veg, like overripe tomatoes or a handful of frozen peas. Use a mixture of fish and feel free to add a few mussels or prawns in too, just make sure it’s sustainable to help protect our fishies (see why that’s important here). Check for the MSC label or ask your fishmonger what he recommends.
sea salt and black pepper
1 large onion or 1 leek
1 stick of celery
optional: 1 small fennel bulb
oil or butter
1 bunch of fresh parsley or dill, leaves picked and stalks reserved (or use the frozen or dried equivalent)
400g sustainable fish fillets scaled and pinboned (we used pollock, coley and smoked undyed haddock)
3 tablespoons flour
For the celeriac mash topping
1 large celeriac, peeled
1 knob of butter
25g hard cheese, such as Parmesan or Cheddar
optional: nutmeg, for grating
Preheat the oven to 180ºC/350ºF. To make the mash topping, chop the celeriac into 2cm cubes, then add to a large pan with about 200ml of water. Place over a medium-high heat, then cover and steam for 10 to 15 minutes, or until tender. Drain well and return to the pan with the butter. Grate in most of the cheese and mash well. Season to taste with salt, pepper and a grating of nutmeg, if you have it.
Reserving the trimmings, peel the onion and trim the carrot, celery and fennel (if using), then finely chop. Add to a large pan over a medium heat with a splash of oil or a little butter, then cook gently for 10 to 15 minutes, or until softened.
Meanwhile, add the milk, vegetable trimmings and parsley stalks to a medium pan over a medium heat. Add the fish fillets, bring gently to the boil, then simmer for 5 minutes. Use a slotted spoon to remove the fish to a plate, then strain the milk into a jug, discarding the trimmings.
Once the veg has softened, add the flour to the pan, stirring continuously for 1 minute. Stir in a spoonful of the warm milk, then gradually add the rest of it, stirring continuously until thickened. Remove from the heat and season to taste, then finely chop and add the parsley leaves.
Flake the fish into a baking dish, spoon over the vegetable mixture, then top with the celeriac mash. Grate over the remaining cheese, then place in the hot oven for 30 to 35 minutes, or until golden and bubbling. Serve just as it is, or with seasonal greens.