In a large mixing bowl mix the dry ingredients and add the butter and egg yolk, have a cup of ice-cold water with a tablespoon ready but don't use the water yet!
Start to incorporate the butter and flour mixture together until it has a crumble like consistency / the consistency of wet sand.You can do this by hand or using a food processor
Now add a tablespoon of water at a time until the dough starts to come together. I normally use about a quarter of a cup but, every time you make this the amount of water will probably change, so go slow and steady
Place the dough onto a clean surface and knead with a bit of flour until the pasty is not sticky and well combined and soft and form into a round discWrap in cling film and chill in the fridge for at least an hour
Take the pastry out of the fridge 20 - 30 minutes before rolling out
Blueberry Mixture
Mash the berries roughly with a fork, if you are using frozen berries let them defrost first and drain any excess liquid before mashing
Stir in the sugar, lemon juice and vanilla then add in the cornflour and mix thoroughly making sure that there are no lumps of cornflour left in the mixture
Now, cover and let the filling sit for at least an hour in the fridge to meld the flavours together, dissolve the sugar and thicken the mixtureYou could leave this mixture in the fridge for up to a day if desired
Vanilla Glaze
In a bowl mix together all of the ingredients
Whisk thoroughly so that there are no lumps and set aside until needed
Making the Pastries
On a floured surface cut the dough into quarters and roll the dough pretty thin or to about the thickness of a coin on a floured surface
Use a round cookie cutter or a round mug to cut out circles of dough, two circles per hand pie
On one circle of dough put 1 teaspoon of the blueberry mixture, dip your fingers into water and run them around the rim of the pastry and place on another circle of dough
Seal the edge with a fork and prick three times to release some steam and egg wash, then sprinkle with some granulated sugar
Bake at (180 degrees Celsius / gas mark 4 / 355 Fahrenheit) for 15 - 25 minutes or until golden brown and crisp
Let the pies cool and then top in a zig-zag pattern with the vanilla glaze, once the glaze sets the hand pies are ready to eat
Notes
- You will need extra flour for rolling out, kneading and dusting- You can use frozen berries if fresh blueberries are not available- Make sure to taste the berries before making the filling in order to gauge how much sugar if required