• Preheat the oven to 425 F.
• In a large mixing bowl, combine the gluten-free flour, sugar, and salt, whisking until well blended.
  1 ¼ cup high quality gluten-free all purpose flour containing xanthan gum, ½ teaspoon granulated sugar, ½ teaspoon salt
• Add the cold, cubed butter and use a dough cutter to work it into the flour until the mixture resembles small peas. Don’t have a dough cutter? You can grate the cold butter with a cheese grater.
  8 tablespoon cold unsalted butter, cubed
• Stir in the sourdough discard, vinegar or lemon juice, and 1 to 2 tablespoons of milk with a fork until the mixture forms large crumbles.

  Then, use your hands to press the dough together, adding extra milk one tablespoon at a time as needed, until it forms a cohesive ball or disc (I used 5 tablespoons total).

  The dough will feel dense and compact but will bake into flaky layers.
  ½ cup cold gluten free sourdough discard, 1 teaspoon vinegar or freshly-squeezed lemon juice, 2-6 tablespoon milk
• Wrap the dough in plastic wrap and chill while preparing the pie filling—at least 20 minutes. It can also be chilled overnight, or up to 2 days.

  Chilling overnight allows the dough to ferment longer, creating a slightly tangy flavor, which works well for savory pies. Avoid long fermentation for sweet pies with delicate flavors like cinnamon or lemon.

After the dough has chilled:

• Use a dough cutter to divide the disc into sections—cut into 4 pieces for mini pies (top crusts only). Note: For a standard 9-inch top or bottom crust, cutting isn’t necessary.
• Place a piece of parchment paper on the counter and set one section of the dough on top. Cover with another piece of parchment paper, then roll out the dough with a rolling pin to the width of the pie pan, ideally ¼-inch thick. The parchment prevents sticking and makes it easy to lift and transfer the rolled-out dough into the pie pan.
• Remove the top piece of parchment and set it aside. Carefully lift the bottom parchment to position the crust over the filled pie pan, then seal the edges with the tines of a fork.
• Repeat with any remaining sections of dough.
• For the Egg Wash: Whisk together the egg and milk in a small bowl. Use a pastry brush to coat the top and edges of the pie evenly.
  1 large egg, 1 tablespoon milk
• Bake for 30 to 45 minutes, keeping a close eye on the pies, until the filling is bubbling (165 F) and the crust is golden brown. Mini pies will bake faster, about 25 to 40 minutes. If the crust starts to brown too quickly, tent with foil.
• Let the pie cool completely before storing or serving. For pot pies, enjoy them warm.