Preheat your oven to 400°F (200°C).
In a bowl, mix flour and salt for the pastry.
Cut in cold butter until the mixture resembles coarse crumbs.
Add cold water gradually until the dough forms.
Wrap the dough in plastic wrap and refrigerate for 30 minutes.
Roll out the dough on a floured surface to 1/8-inch thickness.
Cut out circles using a pastry cutter or glass.
Fill half of each circle with your chosen filling.
Fold the dough over and seal the edges with a fork.
Brush tops with egg wash and bake for 25 minutes until golden brown.