Heat the oil in a large saucepan and saute the garlic, onion and mushrooms for 1 minute.
Meanwhile, toss the Tenderbeef through the seasoned flour, then add to the oil.
Cook for 2-3 minutes until lightly browned, then add the next 9 filling ingredients.
Stir and simmer for 1 1/2 hours, stirring occasionally.
When cooked and thick in consistency, spoon into a 1.8 litre pie dish and top with the cheese.
Roll out the pastry on a lightly floured bench to cover the pie dish plus an extra 5cm/2in.
Cut a 2.5cm/1in-wide strip from the outer edge and place onto the dampened rim of the dish.
Brush with milk, then cover with pastry lid. Press the edges to seal. Decorate with surplus pastry and brush with milk.
Bake at 200c for 40 minutes until golden.