Mix together ripe/active sourdough starter with all-purpose or bread flour and water. Cover loosely and let sit 3-4 hours at 78-80°F until doubled, bubbly & peaked.

To a large bowl, mix together ripe levain with water, granulated sugar and lemon zest. Whisk together. Then add salt and bread flour. Mix together until a wet and sticky dough forms and the ingredients are fully combined. Cover and let rest for 30 minutes.

Perform a series of 'stretch and folds' over the next 1 ½ hours to strengthen the dough. Wet your hand, reach around the dough, pull it up and over, place it on top, turn the bowl a quarter turn and repeat.

After the dough has rested 30 minutes into bulk fermentation, perform the first stretch and fold.

30 minutes later, add fresh blueberries and perform the second stretch and fold.

Another 30 minutes later, stretch and fold again for the third time to disperse blueberries.

30 minutes later, perform a final stretch and fold to strengthen the dough.

Cover the dough and let rise for 2-2.5 more hours at 78ºF.

Tip the bowl upside down onto a clean counter surface and pre-shape the dough into a ball.

Let the dough rest uncovered for about 30 minutes at room temperature.

Prepare a bowl or banneton for shaping the dough and gently shape into a tight ball.

Cover the dough and refrigerate overnight or up to 14-20 hours for cold fermentation.

Preheat the Dutch oven to 450°F for 20 minutes before baking.

Score the dough with a sharp knife before placing it in the Dutch oven.

Bake for 25 minutes at 425°F, then lower the temperature to 400°F for an additional 20 minutes until the loaf reaches 200-210ºF.

Remove the bread from the Dutch oven and let it cool completely before slicing.