Pastry: Sift the flours and then rub in the butter. Sift in the icing sugar then stir in the egg yolk and water. Combine well into a dough. Work the dough into a ball then wrap in plastic wrap and put in the fridge for an hour.
Preheat oven to 180 degrees C and grease a 12 hole muffin tin.
Pies: Roll 2/3 of the dough on a floured surface until it's about 2mm thick. Cut out circles to fit the muffin holes and place in the tray, gently pushing in to create the pie bases.
Fill each pie base with a generous teaspoon of mince, but don't overfill.
Roll out the remaining pastry, using a ruler and a knife cut small slits in the pastry with alternating gaps. When complete the pastry can be pulled gently and it will concertina out; cut the size required for the pie top and place on top then seal the edges.
Bake for 15 minutes. Let cool for a few minutes then remove to a rack to cool off.