In a large mixing bowl add the water, active sourdough starter, and salt and dissolve.

Add the flours and mix until just incorporated. Cover and let it sit for 30 minutes for an autolysis step.

Knead the dough for a few minutes incorporating short resting periods (5 mins). If you are using fresh blueberries add them when the dough starts getting some consistency.

If you're using thawed frozen blueberries, add them now with a lamination step.

Perform 3-4 sets of stretch-and-folds every 30-40 minutes. To do a stretch and fold, wet your hands, lift one side of the dough, stretch it up, and fold it over itself. Rotate the bowl and repeat on all four sides.

Cover and let the dough ferment at room temperature for 6 hours at 72°F/22°C or until it looks bubbly and airy but not wobbly.

Gently turn the dough out onto a lightly floured surface. Preshape it into a boule.

Cover with a floured cloth or bowl, and let it rest fo 30 minutes to 1h.

Finish shaping the dough into your preferred shape and place it in a floured banneton seam side up.

Cover and refrigerate for 12 or overnight.

Preheat your oven to 450°F (230°C) with a Dutch oven or baking stone inside.

Carefully turn the dough out onto a piece of parchment paper. Score the top of the loaf with a sharp blade. Transfer the dough into the preheated Dutch oven, cover with the lid, and bake for 20 minutes. Remove the lid and bake for another 20-30 minutes, until the crust is deeply golden or inner temperature reaches 205°F or 96°C