- Place flour, 1/3 cup sugar, tapioca starch, lemon zest, and salt in a food processor. Pulse a few times until everything is incorporated. Add the butter and let the motor run until the mixture forms into a dough.
- Transfer the dough to a sheet of parchment paper or plastic wrap and form into a log about 2 inches in diameter. Wrap the log with the plastic wrap and twist the ends to seal. Allow to chill in the refrigerator until firm, 30 minutes or up to 1 week.
- Preheat the oven to 350ºF. Remove the dough from the plastic wrap and slice into 1/4 inch rounds. Place the cookies on a parchment lined baking sheet and bake 12 minutes or until just beginning to brown on the edges.
- Allow the cookies to cool completely on the pan. Turn them upside down and dust completely with powdered sugar, then flip over and dust the tops.
- All-purpose flour x 1 cup
- Confectioner’s sugar, plus more for dusting the cookies x 1/3 cup
- Tapioca starch x 1/3 cup
- Lemon zest x 1 tablespoon
- Pinch of salt x 1
- Butter, cold and diced x 3/4 cup