Step 0: Sourdough Starter - Make a starter that takes about 3–5 days.
Step 1: Leaven - Mix 50 g sourdough starter, 200 g water, and 200 g flour. Let sit for about 12 hours.
Step 2: Forming a Dough - Mix 700 g water and 200 g leaven together in a large bowl. Add 900 g white flour and 100 g whole wheat flour. Let sit for 30 minutes. Add 20 g salt and 50 g water, squish dough to mix.
Step 3: Bulk Fermentation - Turn the dough every half hour for 3 hours.
Step 4: Shaping & Proofing - Dump out dough, divide in half, shape into balls, and proof for 3–4 hours or in the fridge for 10–24 hours.
Step 5: Baking - Heat dutch oven to 260°c (500°f), turn dough into it, score, reduce temperature to 230°c (450°f), and bake for 40 minutes.