Preheat the oven to 200°C/Gas mark 6.
Heat the oil in a large frying pan and add the onions and garlic. Cook for 2-3 mins.
Add the turkey, potatoes, peas, carrots, tarragon and gravy and mix well.
Spoon into a large, deep oval dish.
Brush the top of the baking dish with egg, then lay the pastry over. Press down well and decorate the edges by scoring with a knife.
Brush the top of the pastry with beaten egg, then make 2-3 slits in the top of the pastry.
Bake for 35 mins.
Serve with pickled red cabbage and pickled walnuts.
Copyright Phil Vickery