Gluten Free Pie Crust

This is a really good pie crust!

1/3 C brown rice flour
1/3 C tapioca flour
1/3 potato starch (arrowroot would probably work for this but I haven't tried yet)
2 tsp sugar
1/2 tsp baking powder
1 1/2 tsp xanthan gum
1/2 tsp salt
1/2 C unsalted butter, chilled (I bet coconut oil could be subbed but haven't tried it)
1 egg
1 tsp apple cider vinegar

Sift dry ingredients, cut in butter. The dough should hold together when squeezed. Beat egg w/vinegar and mix in dough. Form dough in to a ball. Roll dough out with tapioca flour. Form in pie plate. Pre-bake pie crust in a 450 degree oven for 18 minutes.