1. Preheat oven 220ÂºC/425ÂºF/Gas Mark 7, 15 minutes before baking. Heat the oil in a pan and sautÃ© the onion, mushrooms and red pepper for 3 minutes. Sprinkle in the flour and cook for 2 minutes then draw pan off from the heat.
2. Gradually stir in the stock, return to the heat and cook, stirring until thickened. Remove from the heat and stir in the diced turkey, cooked rice, cream or fromage frais, seasoning to taste and the tarragon. Cover and leave until cool.
3. Roll the pastry out on a lightly floured surface to a 30 x 15cm / 12x6 inch oblong. Place the cooled filling on the rolled out pastry oblong and brush edges lightly with a little beaten egg. Fold the pastry over encasing the filling, then seal the edges firmly knocking them together with the back of a knife.
4. Place on a lightly dampened baking sheet and allow to relax in the fridge for 30 minutes. Make 3-4 slashes across the top of the pastry and brush with the beaten egg.
5. Cook in the preheated oven for 20 minutes. Brush again with a little more egg and continue to cook for 10-15 minutes or until well risen and golden brown