Caper, lemon and dill fish pie with puff pastry top

Method

1. Heat the oven 220°C/200°C fan gas 7. Put the cod in a non-metallic bowl, cover with the salt, then leave for 20 minutes (see Know-how). Thoroughly rinse the fish, then pat dry.
2. Meanwhile, heat a glug of oil and the butter in a flameproof casserole over a medium heat. When the butter has melted, add the onion and leeks and fry for 10 minutes or until softened. Stir in the garlic, mustard and flour, then cook for 1 minute. Add the wine and beat with a wooden spoon until smooth.
3. Slowly stir in the stock, cream and juice of ½ lemon and cook, still stirring, for 5–10 minutes until the sauce is thick enough to hold its shape (see tip). If it isn’t quite there, turn the heat to low and keep stirring. Taste and add more lemon juice if it needs it.
4. Turn off the heat, then stir in the fish, prawns and parsley. Pour into the baking dish(es).
5. Roughly chop the capers and mix with the fresh dill. Stir the caper mixture into the fish pie filling in the baking dish.
6. Roll out the puff pastry on a lightly floured surface to fit the top of the pie dish with a 3-4cm overhang. Cut off thin strips from the edges of the rolled- out pastry to line the edge of the dish. Wet the edge with water, then lay the strips on top. Wet the pastry strips, then lay the large piece of pastry on top to cover the filling.
7. Brush with the egg yolk beaten with a splash of double cream, then trim off any overhanging pastry with kitchen scissors (decorate the top of the pie with the trimmings, if you like). Using a fork, prick the pastry a few times to let out the steam, then bake for 30-35 minutes until the pastry is golden and puffed.