Summer Fish Pie with a Potato Rosti Topping

You tend to think of fish pie as a winter warmer but I love it and wanted to make it more summery. I looked up a few recipes and patched this together from them all.

It is so good I think I will make it this way from now on. The rosti topping gives a lovely contrast in texture much better than the usual mash. By varying the vegetables included you can row with the seasons. For winter include a mirepoix.  It is also a great way to disguise vegetables for small people.

For the filling:
500g mixed fish (cod, natural smoked haddock, salmon etc.)
200g of prawns, mussels or squid (adds interesting texture but is optional. If using frozen defrost and dry or they will make sauce very sloppy)
1 medium onion finely chopped
1 garlic clove crushed
1 stick of celery very finely chopped with a few celery leaves
half a fennel bulb finely sliced
A good handful of petit pois 

tablespoon rapeseed oil
2 tbsp flour
25g butter
200ml milk
Half a lemon juiced
1 tablespoon cream
1 tsp wholegrain mustard
sprig fresh thyme
salt and pepper

Pour a small amount of milk in the bottom of a saucepan and add your fish (not the shell fish). Just cover with more milk and put on hob on a low heat until the milk becomes too hot to hold your finger in. You just want to flavour the milk not cook the fish. Remove the fish with a slotted spoon. Pour off milk and reserve. Set fish aside.

Using this pan add butter and melt, add flour and make a roux. Gradually add the reserved milk to make a thick sauce. Add the mustard, lemon juice, cream, a pinch of salt and a good pinch of black pepper. If you need to add more milk do but try to keep the consistency thick as when you add fish back it will loosen it up. Leave to cool.

Meanwhile soften the vegetables in another pan in the rape seed oil. Cover and cook on a low heat for a few minutes. You need to cook them as they won't cook in the pie. Season.

Cool the vegetables and mix into the fish, add the shellfish and the sauce and mix gently. Pour into an ovenproof dish.

For the topping:
4-5 large potatoes (waxy or new)
25g butter
zest of a lemon
5 tsp of capers

Cook the potatoes in their skins in boiling water for 10 minutes. Remove, cool and skin. Grate them coarsely. Melt the butter in a pan and add lemon zest and capers. Toss the butter mixture through the grated potatoes.

Pile it on top of the fish filling but don't pack it down.

Pop in a preheated oven at 180 deg for 45 minutes or until browned and bubbling.

Allow to cool slightly before serving.

Serves six very generously with maybe a portion for the freezer. It freezes beautifully and can be made in advance for a dinner party. Just don't add potatoes until about to put in oven. 

It goes great with a chilled glass of Picpoul.