Refresh sourdough starter:

3-4 hours prior to baking, refresh your sourdough starter.

Combine water and starter:

Using a dough whisk or your hands, combine the water and starter.

Mix flour into dough:

Incorporate the bread flour into the starter mixture, mixing thoroughly until a shaggy, sticky dough forms.

Add salt and rest:

Work in the salt with the pincer method: wet your hands to minimize stickiness, then pinch the dough between thumb and forefinger, fold it over, and pinch again. Cover the bowl with a lid, plate, or plastic wrap and let it rest for 20-30 minutes.

Stretch and fold dough:

Perform a set of stretch and folds: gently lift a section of dough and fold it toward the center. Turn the bowl by a quarter rotation and repeat at the 12, 3, 6, and 9 o'clock positions. Do this sequence twice for a total of 8 folds. Cover and let rest for 30 minutes, then do another round of stretch and folds. Cover the bowl with a towel and let it ferment at room temperature (75°F (25°C)) for 1 1/2 to 2 hours, or until nearly doubled in size.

Shape and proof dough:

Shape the dough into a boule (round) or batard (oval). Dust a banneton with brown rice flour, place the dough seam-side down in the basket, dust the top with more brown rice flour, and cover with plastic.

Cold proof overnight:

Refrigerate the banneton for a cold proof of 12-18 hours.

Preheat Dutch oven:

Preheat a Dutch oven in a 450°F (230°C) oven for at least 30 minutes.

Score and bake bread:

Remove the dough from the fridge and turn it out onto parchment paper. Score the top and promptly transfer it to the hot Dutch oven to minimize time at room temperature. Bake covered at 450°F (230°C) for 20 minutes, then uncovered for 15-20 minutes.

Cool bread completely:

Take the bread out of the Dutch oven and let it cool on a wire rack for 30-60 minutes before slicing. Patience is key; internal baking continues during this period.