Mushroom and leek pie

Preheat the oven to 200 ºC (400 ºF). Spray a 22 x 18 x 7 cm oven dish with non-stick spray or grease well. Heat the oil in a pan and stir-fry the onions for 3 minutes. Add the leeks and stir-fry for another 5 minutes. Add the mushrooms and stir-fry until lightly browned. Set aside. Melt the butter in a saucepan and stir in the cake flour. Heat for about 2 minutes. Slowly stir in the stock (dissolved in 250 ml (1 c) boiling water), and wine, heating until the sauce comes to the boil and thickens. Stir continuously. Add the seasonings and cream and mix. Mix the sauce with the onion mixture and turn into the prepared oven dish. Roll out the pastry until slightly thinner and place over the vegetable mixture. Trim the edges and cut out shapes from the remaining pastry. Decorate the pie with the pastry shapes and brush with whisked egg yolk. Bake for about 25 minutes or until the pastry is golden brown.
Serves 6-8.