On the day before baking mix all the ingredients in the leaven and
set is aside for 12 hours at room temperature.
Next morning in big bowl, mix the all the ingredients for the dough except salt and leaven and mix everything well and leave it for 30 minutes.
After 30 minutes mix in the salt
and fold the dough for 10 times, and leave it aside for another 30 minutes at room temperature. Repeat the process of folding for another two 30 minutes intervals.
Then leave the dough for about 3-4 hours until it doubles in volume.
see the sourdough activity
Prepare the proofing basket with rice flour and all purpose flour. Transfer the dough to slightly floured surface and shape it into round ball, and transfer to proofing basket.
If you are baking the bread on the same day, leave it for another 3-4 hours. Or transfer the dough to the refrigerator and do a overnight cold fermentation.
When you are ready to bake, preheat the oven 475F, you can preheat the oven with Dutch oven or pizza stone. If you are done overnight cold fermentation, then transfer the dough to parchment paper dusted with cornmeal.
Carefully remove the lid of Dutch oven and transfer the dough, if you want you can score them.
And close Dutch oven with lid and bake it for about 20 minutes. Then remove the lid and parchment paper and bake it for another 15 minutes and if the bread is not dark brown give another 5 -10 minutes.
Let cool the bread for 45 minutes and then slice and enjoy.