7:00 AM – Starter Initialization: In a clean glass jar, add the 5g of mature sourdough starter culture to 35g of room-temperature water and whisk together thoroughly until completely loose.

Flour Incorporation: Stir in the 30g of all-purpose (or bread) flour and 5g of rye flour. Mix well until no dry pockets remain, cover loosely, and let it sit at room temperature 74–78°F (23–26°C) for 8 to 10 hours until the starter reaches its peak and triples or more in volume.

4:30 PM – The Flour Hydration: In your stand mixer bowl, combine the 207g of baseline water with 270g of bread flour and 30g of whole wheat flour. Mix with a heavy spoon or your hands just until a shaggy, raw dough mass forms and no dry spots remain. Cover the bowl and let it rest for 1 full hour to complete the autolyse, fully hydrating the flour and activating natural gluten development.

5:30 PM – Levain Integration: Pour 60g of your mature, peak-ripened levain directly over the autolysed dough.

Mechanical Mixing: Secure the bowl in your stand mixer fitted with the dough hook. Mix on low speed for 2 to 3 minutes (or use speed 3 on a KitchenAid mixer for 3 to 4 minutes) until the starter is completely incorporated. Cover and let the dough rest for 30 minutes.

6:00 PM – Salt and Bassinage Addition: Sprinkle the 6g of fine sea salt and the optional lemon zest evenly over the dough surface, then pour in the reserved 18g of extra cold water. This bassinage process adds a secondary splash of liquid to tighten the gluten network while bringing the total hydration safely to 75%.

High-Speed Emulsification: Mix on a low speed for 2 to 3 minutes (or KitchenAid speed 3 for 5 to 6 minutes) until well incorporated. The dough should pull together into a cohesive ball but remain slightly sticky on the bottom. Cover and leave to rest for 30 minutes at 74–78°F (23–26°C).

6:30 PM – The Blueberry Lamination: Mist your work surface lightly with water and wet your hands. Tip the dough onto the counter and gently stretch it outward horizontally and vertically as thin as you can go without ripping it. Spread your 75g to 100g of fresh, bone-dry blueberries uniformly across the entire surface of the stretched dough sheet. Fold the dough cleanly like a letter into thirds, roll it up into a compact package, and place it back into a clean proofing container. Let rest for 45 minutes.

Progressive Structural Folds: Continue building vertical dough strength around the wet berries by executing regular stretch-and-folds: 1st fold at 7:15 PM, 2nd fold at 8:00 PM, and the 3rd/final fold at 8:45 PM. Be gentle during these folds to avoid popping the berries prematurely.

Final Bulk Proof: Following the final fold, let the dough proof undisturbed for 30 minutes at 76–80°F (23–26°C). Look for a distinct lightness, small surface bubbles, and a 40% to 50% volume expansion.

9:15 PM – Preshaping: Transfer the fermented dough out onto your work surface and dust the top lightly with flour. Using your scraper, flip the dough over so the floured side faces down against the counter. Fold the dough cleanly onto itself so that the flour remains entirely on the outside of the loaf, shape into a round ball, and let it rest uncovered on the counter for 30 minutes to relax the gluten.

9:45 PM – Final Shaping: Dust the top with a little more flour and use a scraper to flip it over floured-side down. Pull the side closest to you up, pull the right two corners over to the left, fold them up into the half of the dough, and repeat on the opposite side. Roll the dough tightly away from you into a smooth, taut, high-tension cylinder (log shape) or round boule.

Basket Transfer & Cold Retard: Place the shaped loaf seam-side up into a prepared proofing basket heavily dusted with flour (rice flour mixed with bread flour works best). Cover it loosely with plastic wrap to trap the moisture. Immediately transfer the covered basket into the refrigerator to undergo a slow cold fermentation for 14 to 24 hours.

The Next Day – Oven Preheating: Place your cast-iron Dutch oven and its lid inside your home oven. Turn the temperature up to 500°F (260°C) and let it preheat thoroughly for 45 minutes to 1 hour.

Inversion and Scoring: Remove the cold dough basket directly from the fridge. Invert it cleanly onto a sheet of parchment paper. Use an ultra-sharp knife or scoring lame to cut a clean decorative slash across the crown.

The Dutch Oven Bake: Carefully transfer the dough into the smoking hot cast-iron pan using the parchment paper handles. Cover tightly with the lid to lock in the escaping steam and bake at 500°F (260°C) for exactly 15 minutes.

The Crisp Finish: Remove the lid to vent the steam, reduce the oven temperature down to 450°F (232°C), and continue baking uncovered for an additional 20 minutes until the crust achieves a deep golden-brown finish with dark purple tones where berries peek through. Transfer the baked loaf onto a wire rack and let it cool completely before slicing.