Heat a tablespoon of oil in a large pan and lightly brown the apple pieces then remove and set aside.
Add a little more oil to the pan and cook the leeks and sage for 3 – 4 mins until softened.
Add the flour to the pan and cook for a couple of minutes then add half the cider, stirring until smooth before adding the remainder.
Bubble for 2 minutes then add the stock, pork and apple pieces. Cover and simmer gently for 10 – 15 mins.
Meanwhile, heat the oven to 220C/fan 200C/gas 7.
Roll out the pastry to the thickness of a pound coin and cut out four circles big enough to cover 4 small pie dishes.
Divide the pork mixture between the dishes and brush the rims with milk.
Lift the pastry on to the pies, trimming off any excess.
Press down and crimp the edges with a fork then cut a couple of slits in the top of each to let the steam out.
Brush with milk and bake for 15-20 minutes, until the pastry is risen and golden brown.