Ensure your sourdough starter is active and bubbly. Feed it 4-12 hours before starting the recipe for optimal results.
In a large bowl, combine the active starter and water. Stir until the starter dissolves.
Add the bread flour and lemon zest. Mix until a rough dough forms.
Let the dough rest (autolyse) for 30 minutes.
After the autolyse period, sprinkle the salt over the dough.
Wet your hands and gently mix the salt into the dough until fully incorporated.
Perform the stretch and fold technique every 30 minutes for 2 hours:
With wet hands, gently pull one side of the dough up and over the center.
Rotate the bowl 90 degrees and repeat the stretch and fold on the next side.
Continue this process until all sides have been folded.
During the second set of stretch and folds, gently fold in the fresh blueberries to distribute them evenly throughout the dough.
After the stretch and folds, cover the bowl and let the dough rise until it doubles in size. This can take anywhere from 4 to 12 hours, depending on room temperature and starter activity.
Gently transfer the dough onto a lightly floured surface.
Shape it into a round loaf by folding the edges into the center and then rolling it gently.
Place the shaped dough seam-side up in a proofing basket or bowl.
Cover and let it proof for 2-3 hours at room temperature, or refrigerate for 8-12 hours for cold proofing.
Place a Dutch oven (with lid) inside your oven and preheat to 450°F (230°C) for at least 30 minutes.
Carefully remove the preheated Dutch oven from the oven.
Place a piece of parchment paper over the dough and invert it onto the parchment.
Score the top of the loaf with a sharp blade.
Using parchment paper, transfer the dough into the preheated Dutch oven.
Cover and bake at 450°F (230°C) for 20 minutes.
Remove the lid, reduce the temperature to 400°F (200°C), and bake for an additional 15-20 minutes until the crust is golden brown.
While the bread is baking, prepare the glaze by mixing powdered sugar and lemon juice until smooth.
Once the bread has cooled, drizzle the glaze over the top for added sweetness and shine.
Allow the bread to cool on a wire rack for at least 1 hour before slicing to ensure the interior sets properly.