Combine the sourdough starter, water, olive oil, and egg. Whisk to combine. Stir in salt and tapioca flour. Add ½ cup of sorghum flour and stir to combine. Add more sorghum flour as needed to make a soft dough that can be kneaded. Flour a surface with tapioca and knead the dough a few times to bring it together.
Grease a bowl and turn dough into the bowl to oil the bottom then flip so that oiled portion is facing up. Cover with a tight lid or plate and sour for 8-24 hours.
Preheat oven to 450°F.
Oil a large rectangular baking pan or two smaller round pizza pans. Press the dough out into the pan, using wet fingers if the dough is sticky. Create a lip at the edge of the crust.
Dock the dough all over with a fork and bake for 10 minutes or until it just starts browning around the edges.
Remove from oven, top with favorite toppings, and return for an additional 20-25 minutes, or until cheese is melted and toppings are cooked.
Remove and allow to cool briefly before slicing and serving.