Make sure you begin with a good sourdough starter. Look for plenty of active bubbles, which will help your bread to rise.
Mix the sourdough starter, warm water, and salt in a medium-sized bowl using a spatula. Add the bread flour and mix with the spatula until no lumps remain. Cover and rest for 30 minutes.
After 30 minutes, turn out the dough onto a floured surface and sprinkle with additional flour. Your dough will be very sticky, get used to it! Using the slap & fold method, knead the dough for five minutes. Using a pastry scraper can make this process easier.
Proof, covered, for 4 hours in a warm spot. A good place to leave it is in the oven with the oven light on. After four hours, remove from the oven.
Knead the dough again for five minutes using that stretch and fold method, sprinkling with flour as needed. Cover and allow to rest for 30 more minutes.
For the last time, fold the dough, as if making an envelope, onto itself, until the dough forms a nice tight ball.
Flour the Banneton basket generously using a mixture of rice flour and the regular white flour. You don't want the dough to get stuck in the basket, so don't skimp on the flour. Sprinkle some rice flour and regular flour on top of the dough as well. Carefully transfer the dough into the basket, seam-side-up. Cover and proof in a refrigerator overnight.
Remove the basket from the fridge two hours before baking.
Sprinkle cornmeal on a cutting board or pizza peel. Place a 3.5 quart Dutch Oven in a 450-degree oven for 15 min to heat. Gently remove the dough from the basket and place seam-side-down onto the cornmeal surface.
Carefully remove the heated pot from the oven and lower the dough into the pot. Make a few slashes on top using a sharp knife or a bread lame, if you have one. Using a spray bottle, spray water around the bread a few times. This will help create steam as the bread bakes and will give you an amazing crust. Cover with the lid and bake for 20 minutes.
Remove the Dutch Oven's lid and bake an additional 20 minutes, uncovered.
Carefully remove the pot from the oven and allow to cool before removing the bread.
Cool before slicing with a bread knife. Give it a taste and then stop back to let me know how it went!