In small bowl, mix flours, xanthan gum, salt and baking powder with whisk; set aside. In medium microwavable bowl, microwave tahini, oil and hot water on High 5 seconds; stir with whisk until blended. Add tamari and flour mixture; stir until blended. Reserve 2 tablespoons toasted sesame seed for topping. Stir remaining sesame seed into dough.