Make The Slurry. In a small bowl, combine cold water, and 1/3 cup gluten-free flour. Whisk or stir until well blended and evenly combined. Set aside.
Combine. In a food processor, combine 2 cups gluten-free flour, the shortening, sugar, and salt. Pulse briefly to combine--there will still be clumps! (Alternatively, you can use a pastry blender to mix the shortening into the dry ingredients.)
Add Slurry. Pour the slurry over the pie dough mixture and pulse to combine until the mixture starts to come together. It will still be quite sticky--this is normal! Don't add extra flour!
Shape The Dough. Sprinkle about 1 Tablespoon gluten-free flour onto your countertop and scoop the dough mixture out onto the floured countertop. Use your hands to gently shape the dough into a ball.
Divide The Dough. Use a knife to divide the pie dough in half. Shape each half into a disc shape. If not baking right away, wrap each dough disc well in plastic wrap and chill or freeze until ready to use. (Thaw chilled or frozen dough and bring to room temperature before using.) Roll. If using right away, place one disc of dough between two large sheets of parchment paper and roll pie dough out into a 9-10 inch circle (about the size of your pie pan). Transfer the dough to your pie pan--I remove the top sheet of parchment, then place my pie pan face down onto the rolled out dough. Then, I flip it over right side up.
Crimp The Edges. Adjust the crust so it's evenly placed in the pan, using your fingers to gently patch up any cracks. Even out the border of the crust with your fingers, then crimp the edges of the crust. I use two fingers from one hand in a pinching shape, then indent the crust with one finger from the other hand. (See photos & video for visual)
Bake. Then, follow the baking directions of your pie recipe--fill with pie filling and bake, or blind bake the crust (if directed), and fill after cooling. (aka if your pie recipe says to bake 45 min, bake for 45 min)