Awesome alternative way to use up your left over Sunday lunch....
method
Preheat oven to 220°C/425°F/Gas Mark 7, cut your pastry into long rectangle shapes and roll slightly, then place your leftover Sunday lunch on one half of the pasty, leaving a border around the edge and brush the edges with the egg yolk. Fold the uncovered half over to cover the mix, press the edges together to form a good seal and knock up the edges with a sharp knife.
Make two slits in the top of the pasty and brush with egg glaze and bake for 15 minutes until pastry is risen and golden, serve with dollops of horseradish sauce