01 - In a large bowl, combine the bread flour, whole wheat flour, and water. Mix until just incorporated, ensuring no dry flour remains. Cover the bowl and let rest for 1 hour to hydrate the flour.
02 - Add the active sourdough starter and sea salt to the autolysed dough. Mix by hand or using a spatula until fully incorporated, approximately 3-5 minutes. The dough should become cohesive and start to develop some structure.
03 - Cover the bowl and let ferment at room temperature for 4-5 hours. Every 30-45 minutes, perform a stretch and fold: grab one edge of the dough, pull it upward, and fold it over the center. Rotate the bowl and repeat 4 times per session to strengthen the gluten network.
04 - Turn the dough onto a lightly floured work surface. Gently shape into a round boule, using a bench scraper to create tension on the surface. Cover and let rest for 20 minutes to relax the gluten.
05 - Shape the dough into a tight round loaf, creating surface tension by folding the edges toward the center and flipping seam-side down. Place the dough seam-side up in a well-floured proofing basket or bowl lined with a floured kitchen towel.
06 - Cover and let rise at room temperature for 2-3 hours until the dough shows slight resistance to gentle touch and has increased about 50% in volume. For enhanced sour flavor, refrigerate overnight for 8-12 hours.
07 - Position a Dutch oven or heavy oven-safe pot with lid in the center of the oven. Preheat to 480°F for at least 30 minutes to ensure the pot is thoroughly hot for optimal oven spring.
08 - Gently invert the dough onto parchment paper. Using a sharp blade or bread lame, score the surface with a single slash or cross pattern. Transfer to the preheated pot, cover with lid, and bake for 20 minutes. Remove lid, reduce temperature to 430°F, and bake 25 minutes until deep golden brown with an internal temperature of 200°F.
09 - Remove the bread from the pot and transfer to a wire rack. Cool completely for at least 2 hours before slicing to allow the crumb structure to set and prevent excess moisture loss.