1. Make the Preferment: The night before baking, mix the starter, water, and brown rice flour. Cover loosely and leave on the counter for 8-12 hours until puffy and bubbly.

2. Prepare Liquids: In a large bowl, whisk together the 300g water, maple syrup, and optional olive oil. Sprinkle the psyllium husk over the top and whisk quickly. Let sit for 5-10 minutes to form a gel.

3. Combine Dry Ingredients: In a separate bowl, whisk together the potato starch, tapioca flour, sorghum flour, brown rice flour, and salt until thoroughly combined.

4. Mix Everything: Add the bubbly preferment and the psyllium gel to the dry ingredients. Mix with a stand mixer (dough hook) or by hand until no dry flour remains. The dough will be sticky. Cover and rest for 30 minutes.

5. First Rise (Bulk Fermentation): Keep the dough covered at room temperature for 4-8 hours, or until it looks puffier, feels airy, and has a slight dome on top.

6. Shape Your Loaf: On a lightly floured surface, gently press the dough into a rectangle. Fold the sides in, then roll it up to form a taut ball (boule) or oval (batard).

7. Second Rise (Proofing): Place the shaped loaf, seam-side up, into a generously floured proofing basket. Proof on the counter for 1-2 hours or in the refrigerator for a cold proof of 8-24 hours.

8. Prepare for Baking: Place a Dutch oven with its lid in your oven and preheat to 450°F (232°C).

9. Score and Bake: Carefully place the proofed loaf on parchment paper and lower it into the hot Dutch oven. Score the top with one ½-inch deep slash. Cover and bake for 35 minutes. Remove the lid and bake for another 20-30 minutes until deep golden brown.

10. Cool Completely: Transfer the loaf to a wire rack and let it cool completely before slicing, at least 4-6 hours. This is critical for the crumb to set properly.