Whisk together flours, tapioca startch, cornstarch, yeast, salt, xanthan gum in a large bowl.

Combine liquid ingredients and gradually add them to the dry ingredients with a spoon, food processor or paddle attachment of your stand mixer. (NOTE: I’ve used the proportions in the original recipe but I had to add additional flour because my dough was very runny. Use your own judgement. It should be a very wet loaf but you do need to be able to manage it.)

Cover, but not airtight, and rest at room temperature for 2 hours.

Refrigerate covered (again not air tight) and use within seven days. It will make about 4 loafs.

When you are ready to bake, use wet hands and form a one pound loaf. Shape into a ball and then form into a narrow oval. Place on a pizza peel lined with cornmeal or parchment paper and allow to rise loosely covered with plastic wrap for 90 minutes.

Preheat oven to 450 degrees 30 minutes prior to baking. Place pizza stone in the oven to preheat and put a broiler pan on the bottom rack.

Slide the loaf into the hot stone and quickly pour 1 cup of tap water into the broiler tray and close oven door. Bake for 30 minutes.