Mix. Combine the bread flour, water, sugar, and bubbly sourdough starter in a large bowl. Stir the mixture until a rough dough forms, using your hands to incorporate any dry bits of flour. The dough will be slightly sticky but should come together.
Rest (autolyze). Cover with a clean, damp tea towel and let the dough rest at room temperature for 30 minutes.
Add the salt and fruit. After the 30-minute rest, sprinkle the salt evenly over the dough. Then, gently fold in the blueberries and lemon zest, careful not to burst the blueberries.
Knead. Knead for 1–2 minutes until the salt and fruit are evenly distributed. The dough will feel slightly sticky, but that’s normal—focus on gentle handling to prevent the blueberries from breaking.
First rise + stretch and folds. Cover the dough with the damp towel again and let it rise in a warm place for about 3 hours. During this rise, reshape the dough into a ball once every hour using stretch and folds. Lift a side of the dough up to stretch it and then fold it back down over towards the center. This folding helps strengthen the dough and build a structure for the final loaf.
Second rise (proofing). Generously dust a banneton or a bowl lined with a clean towel with rice flour to prevent sticking. After the 3-hour rise, shape the dough into a tight ball and place it seam-side up into the prepared banneton. Then, cover it with plastic wrap or a damp towel and let it proof overnight in the refrigerator for 8–12 hours. This slow, cold fermentation deepens the flavor of the bread.
Prep for baking. Preheat your oven to 450°F (232°C) the next morning with the Dutch oven placed inside to heat up. Then, remove the dough from the fridge and carefully turn it onto a piece of parchment paper, aiming for it to land in the center. If needed, gently reshape it into a round loaf. Using a sharp knife or bread lame, score the top of the dough with a few deep slashes to allow for expansion during baking.
Bake. Once the oven is preheated, carefully remove the hot Dutch oven and transfer the parchment paper with the dough into it. Cover with the lid and bake for 25 minutes. Then, remove the lid and continue baking uncovered for another 25 minutes.
Finish and cool. For an extra crispy crust, remove the loaf from the Dutch oven and bake it directly on the oven rack for an additional 5 minutes. The bread is done when it reaches an internal temperature of 200°F–210°F (93°C–99°C) and the crust is a deep golden brown. Then, carefully remove the bread from the oven and allow it to cool on a wire rack for at least 3–4 hours before slicing. This cooling time helps set the crumb structure inside the loaf.
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Notes
Using rice flour to coat your banneton will keep the dough from sticking.