Combine the first five ingredients in the food processor and pulse to aerate. Add the diced butter and pulse ten times until the butter is the size of peas. Add the ice water and pulse until it comes together. It will not form a ball. Transfer the dough to your work surface and knead a couple of times. Wrap it in plastic wrap, flatten it, and form it into a disk. Refrigerate for 1 hour.
Dust your preferably cold work surface with superfine brown rice flour. Roll the dough to 1/8-inch thickness. Fill a 9-inch tart mold with the dough. Cut off excess and refrigerate for 20 minutes.
Preheat oven to 375F (190C). Lightly dock the bottom of the tart dough with a fork. Cover it with parchment paper and fill it with pie weights or dried beans. Bake for 20 minutes. Remove beans and bake for another 5 minutes.
Reduce heat to 350F (180C).