Instructions:
- Combine all dry ingredients (flours, salt, yeast) in a large mixing bowl and whisk thoroughly.
- Pour in the cool water and mix by hand or with a spoon until just combined into a shaggy mass. Cover the bowl.
- Rest the dough for 30 minutes (Autolyse). Then, perform three sets of gentle 'stretch and folds,' spaced 30 minutes apart over the next 90 minutes. After the final fold, cover tightly.
- Place the covered dough in the refrigerator for a long, cold bulk fermentation lasting 12 to 18 hours to develop flavour.
- About one hour before baking, place your Dutch oven (with the lid on) inside the oven and preheat to 475°F (245°C).
- Gently scrape the cold dough onto a lightly floured surface. Pre-shape it into a round (boule) and let it rest, covered, for 20 minutes (bench rest).
- Flip the dough and perform the final tight shaping. Place the dough, seam-side up, into a floured banneton basket or linen-lined bowl. Let it proof at room temperature for 45-60 minutes.
- Carefully invert the dough onto a piece of parchment paper. Score the top deeply with a razor blade or sharp knife.
- Using the parchment as a sling, transfer the dough into the preheated Dutch oven. Cover with the lid and bake for 25 minutes.
- Remove the lid, reduce the oven temperature to 450°F (230°C), and continue baking for an additional 20–25 minutes until the crust is a deep, dark mahogany brown.
- Transfer the finished loaf to a wire rack and allow it to cool completely, ideally for at least 2 hours, before slicing.