1 1/2 cups superfine brown rice flour (oat flour)
1/2 cup potato starch (tapioca starch)
1/2 cup tapioca starch (arrowroot?)
1/4 tsp salt
1 cup unsalted butter
Flours and salt in food processor. Pulse a few times. Add butter and pulse 10 times. Add 6 T ice water, Stick together without feeling wet.
Bring dough together without handling too much. Divide, flatten, wrap in parchment and chill in fridge.