Mixing the Dough

1. In a large bowl, mix the active sourdough starter, milk, eggs, sugar, melted butter, lemon zest, lemon juice, and salt.
2. Add the flour and mix until no dry bits remain; the dough will appear shaggy and slightly sticky.
3. Let the dough rest for 20 to 30 minutes.

Folding and Adding Blueberries

1. Perform a set of gentle folds, about 3 times, at 20 to 30-minute intervals.
2. After the first or second fold, sprinkle the blueberries on top and fold the dough over gently to incorporate.

Bulk Fermentation

1. Allow the dough to bulk ferment for 4 to 6 hours, or until it has grown about 50% larger and looks smooth with bubbles appearing.

Shaping and Proofing

1. Gently shape the dough into a rectangle, fold it, and roll into a tight round.
2. Let it proof at room temperature or in the fridge overnight for more flavor.

Scoring and Baking

1. Preheat the oven with the Dutch oven inside.
2. Tip the dough onto parchment and score it with a confident cut.
3. Bake covered for 20 minutes, then uncovered for 20 to 25 minutes, until golden brown and baked through.
4. Let it cool completely before slicing.