Combine starter, flours, and water and mix well in a stand mixer using a dough hook until a soft, sticky dough forms. Add a little more water or flour if needed. Cover dough.

AUTOLYSE - Let dough rest for 20 minutes, then add salt. Using the same dough hook, turn on the mixer and mix well, until fully kneaded. Take the dough out of the mixer bowl and place in a greased bowl.

Cover the dough and let rise for one hour.

Turn the dough out onto a lightly floured surface and fold the dough like a business letter. Pull up on one side and fold over like top of an envelope. Rotate the dough 90 degrees and repeat the business fold. Cover and let rise for one more hour.

Turn the dough out on a lightly floured surface and cut the dough in half. Gently shape the dough into two round shapes, cover, and let rest for 20 minutes.

At the end of this rest period, form your shapes into tight balls and then place seam side up in two towel lined bowls or in lightly floured bannetons. Let rise for 2 to 2 1/2 hours, until light and airy.

45 minutes to 1 hour before you'd like to bake, preheat oven to 450F. Preheat a pizza stone on a middle rack and include a cast iron skilled on the bottom rack.

Before baking, carefully turn the bread out of the banneton onto a piece of parchment paper. Slash or score your bread so it won't erupt during baking.

Place the bread on the preheated stone, quickly pour one cup hot water into the skillet, and shut the door.

Turn the temperature down to 425 F. Bake for 27-30 minutes.

Store any leftover bread in a loose bag at room temperature for about a day to prevent moisture buildup. You can also wrap tightly and freeze for another day.