1. In a small mixing bowl, whisk together 1 ½  cups lukewarm 90f filtered water with the ½  C sourdough starter, then pour the mixture into the bowl with the 3 ½ C  flour mix and 2 tsp salt. Mix until just combined. Cover the bowl with plastic wrap and a damp towel and leave it at *room temperature to rise overnight, from 12 to 24 hours.
2. The next day, the dough should have risen by double and you may see spongy bubbles and a wet texture.  Uncover the bowl and wet your hand and gently stretch one end of the dough up, lift and fold the edge of the dough from the outside up over on top, ¼ turn bowl and fold 4 more times around. Cover, allow to rest for 1 hour. Repeat this process again after another hour.
3. Next, the dough should be ready to shape.  Lightly dust a clean board surface with flour and pour the dough out on top. Then gently fold the edges of the dough lightly from the outside into the center, about 8 folds to form a round loaf by tucking in at the seams.
4. Line a bowl with a clean lint free towel and dust it well with rice flour then place the dough on top of the towel seam side up. Lightly dust the top with more rice flour, cover and allow to proof at room temperature, about 2 hours.
5. Preheat oven to 450f. Place a covered Dutch oven or heavy cast iron pot with a lid into the oven and allow it to heat up for 30 minutes. Cut a square of parchment paper large enough to cover the base of the pan with extra for holding onto the sides. Gently turn the dough over seam side down, onto the parchment paper, removing the towel. Carefully remove the pot from the oven, take off its top, and lower the dough on the parchment paper into it, so that the presentation top side is up. Use a sharp thin knife or razor, to cut a cross score across the top to allow for the rise and the decorative ‘ears’. Cover with the lid and bake it in the hot oven.
6. Bake for about 30 minutes, then take off the lid and allow it to continue to bake uncovered until it is brown and crusty all over, an additional 20 minutes or so. When done, lift the loaf out using the parchment paper sides and allow the loaf to rest on a cooling rack for at least 2 hours to cool for best interior, before slicing into the fresh homemade sourdough bread.

*Room temperatures vary for proofing times and fermenting doughs. 68f-72f is ideal range. Kitchen scale by weight is preferred to volume measuring.