Gluten-free Butter Pie Crust

Gluten-free Butter Pie Crust- makes 2 pie crusts
Source: http://www.gfdoctorrecipes.com/recipes/gluten-free-raspberry-custard-pie-with-a-butter-crust-and-a-preview.html

93 grams ½ cup +1 tablespoon whole grain flour mix
80 grams white rice flour
56 grams ⅓ cup +1 tablespoon white flour mix
58 grams ⅓ cup +1 tablespoon sweet rice flour
4 grams 1 teaspoon organic cane sugar
3 grams ½ teaspoon salt
1 gram Pinch of baking powder
112 grams ½ cup butter
6 grams 1 ½ teaspoon apple cider vinegar
117 grams ½ cup water
Stir together all the flours till you get an even color.
Using your hands, rub the butter into the flour, smearing the mixture between your fingers.
Continue till the mixture resembles sand with a few chunkier pieces.
Add the vinegar and stir.
Add the water a bit at a time, stirring with your hand to incorporate the water.
The dough should hold together with a gentle squeeze.
If you need another tablespoon of water to reach this consistency, that is fine. Everyone’s flours have a different moisture content, just based on regional moisture differences.
Divide the dough in half, form into a neat disc about an inch tall.
Wrap well in plastic and chill for at least ½ hour.
Cover your rolling surface with tapioca flour. Remove one disc of dough from the plastic, sprinkle generously with tapioca flour.
Place on prepared surface and begin to roll.
Roll lightly as a butterfly with almost no downward  pressure. Just allow the dough to move gently flatter, keeping the board and surface of the dough well sprinkled with tapioca flour.