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.

5:00 PM – The Flour Hydration: In your stand mixer bowl, combine the 207g of baseline water with 270g of bread flour and 30g of buckwheat 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.

6:00 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.

6:30 PM – Salt and Bassinage Addition: Sprinkle the 6g of fine sea salt evenly over the dough surface and 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. If mixing by hand, utilize the Rubaud or slap-and-fold method for 10 minutes, using brief stops to let the structure self-tighten. Cover and leave to rest for 30 minutes at 74–78°F / 23–26°C.

7:00 PM – First Stretch and Fold: With wet hands, slide your fingers under one side of the dough, pull it upward gently to stretch it, and fold it over the center. Rotate the bowl 90 degrees and repeat. Perform this on all 4 sides, then cover and rest.

Progressive Structural Folds: Continue building vertical dough strength by executing regular stretch-and-folds spaced 45 minutes apart: 2nd fold at 7:45 PM, 3rd fold at 8:30 PM, and the 4th/final fold at 9:15 PM.

Final Bulk Proof: Following the final fold, let the dough proof undisturbed for 30 minutes at 76–80°F (23–26°C). Keep a close eye on the dough—look for a distinct lightness, small surface bubbles, and a 40% to 50% volume expansion. If the dough rises too quickly due to room temperature, shorten the time between folds.

9:45 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 (this becomes the crust). Shape into a round ball and let it rest uncovered on the counter for 30 minutes to relax the gluten.

10:15 PM – Final Shaping: Dust the top with a little whole wheat or bread flour and use a scraper to flip it over floured-side down. Starting at the side closest to you, pull the right two corners of the dough to the left, then fold them up into the half of the dough. Repeat this identical action on the left side. Finally, roll the dough tightly away from you into a smooth, taut, high-tension cylinder (log shape).

Basket Transfer & Cold Retard: Place the shaped log seam-side up into a prepared proofing basket (banneton or a loaf pan lined with a towel dusted with flour). Cover it loosely with plastic wrap to trap the moisture. Transfer the covered basket directly 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 and remove the basket. 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 color. Transfer the baked loaf onto a wire rack and let it cool completely before slicing.