Notes: *Look for sour cassava flour or sour tapioca flour at Latin American markets. Plain tapioca flour lacks the slight sour, fermented flavor, but makes a great substitute. You can find plain tapioca flour from Bob's Red Mill at most natural foods stores. *Portion the dough onto the baking sheets and freeze until solid. Transfer to resealable freezer bags and freeze for up to 1 month. Bake frozen for the same amount of time. I frozen a batch of pão de queijo and they turned out beautifully when I baked them.