In a large mixing bowl, combine the active sourdough starter with salt and water until it is fully incorporated.

Slowly add the flour and mix well, making sure there are no dry bits of flour.

Cover with a cloth and let it rest for 30 minutes.

Once the dough has rested, add the blueberries and lemon zest.

Gently fold the blueberries and lemon zest into the dough.

Perform a set of stretch and folds every 30 minutes for 3 hours:

Use a little water to wet your hands, grab a portion of the dough and slowly stretch it, taking care not to break it. Fold it towards the center over the dough. Keep turning the bowl and repeat the process until all parts of the dough is covered. This completes one set of stretch and fold. Repeat this process six times at an interval of 30 minutes.

Bulk Fermentation (3-4 hours):

Let the dough sit for bulk fermentation until it is almost doubled and has bubbles on the top. This may take 3-4 hours, depending on the temperature of your kitchen.

Dust round or oval bannetons well with (AP or Rice) flour.

Flip the dough onto a lightly floured surface.

To Shape: Pick one side of the dough and fold it to the center. Pick the other side and fold it to the center. Now hold the dough gently and tuck it to form a log. Carefully place the dough seam-side up on the banneton. (This will be helpful to flip it out for baking)

Cover the dough loosely and place it in the refrigerator overnight for cold fermentation and final rise (6-12 hours).

After the cold fermentation, place a Dutch oven into the oven and set it to preheat to 450 F (230 C) for 45 minutes.

While the oven is preheating, take the dough out of the fridge and let sit until youre ready to bake (45 mins).

Flip it out of the banneton onto parchment paper.

Score the dough using a blade or sharp knife.

Carefully take the Dutch oven out of the oven.

Place the scored dough along with the baking paper into the hot Dutch oven and immediately close the lid (tucking in any parchment sticking out)

Place it back in the oven and bake for 20 minutes.

Remove the lid from the Dutch oven and bake for another 15 minutes.

Let the bread stay in the pot for 15 min before removing.

Cool completely on a wire rack, slice, and serve.