Place flour and salt in a bowl.
Rub in the butter using your fingertips until mixture resembles coarse breadcrumbs.
Mix in the egg yolk using a knife. The mixture should form a firm dough. If it's too dry, add a little cold water.
Roll into a ball and refrigerate while you prepare the filling.
Heat oil in a saucepan and brown the onions.
Add green pepper, mushrooms and garlic and sauté for 2 minutes.
Stir in 400 ml water, tomato soup, turkey and origanum (5 ml if using dried origanum).
Bring to the boil and simmer, covered, for 5 minutes. Season to taste, then set aside to cool.
Spoon cool mixture into a greased pie dish.
Roll pastry out on a floured surface.
Use a sharp knife to cut out leaf shapes. Layer the pastry leaves over the filling.
Brush with egg and bake in a preheated oven at 200 ºC for 30 minutes, or until pastry is golden.