In a large mixing bowl, combine your active sourdough starter with filtered water, stirring until milky. Gradually add bread flour and salt, mixing until no dry flour pockets remain.

Let the dough rest for at least 30 minutes.

Start the stretch and fold technique by gently pulling one side of the dough and folding it over to the opposite side, repeating every 30 minutes for about 2-4 hours.

Allow the dough to undergo bulk fermentation for 6-9 hours at room temperature until it doubles in size.

Gently turn the dough out onto a floured surface, shape it into a rough round, and incorporate blueberries and lemon zest using a lamination technique.

Transfer the shaped dough into a banneton, cover it with a cloth, and cold proof for 8-72 hours.

Preheat your Dutch oven to 450°F about 30 minutes before baking.

Score the top of the dough, place it into the preheated Dutch oven, cover it, and bake for 27 minutes. Remove the lid and continue to bake for an additional 10-15 minutes.

Transfer the loaf to a wire rack and let it cool for at least 1 hour.