Place medium/large mixing bowl on scale. Weight out 350 grams of water, 10 grams of salt and 100 grams of the active sourdough starter. Mix together thoroughly until the starter and salt dissolve into the water.

Next, add 50 grams of whole wheat flour and 400 grams of bread flour. Mix them into the rest of the ingredients until the flour is hydrated and there aren’t any clumps of dry flour left. Then cover up the dough with a kitchen towel and let it rest on the counter for 30 minutes.

This starts the “bulk fermentation” stage. During this stage, the dough gets 3 sets of stretch and folds with 30 minutes of rest between each.

After 3-4 sets of stretch and folds, flip the dough over so the smooth side is facing up, and cover up the dough. Let it continue to rise at room temperature until it has almost doubled in size. This could take another 3-6 hours, depending on the temperature of your kitchen.

When your dough has almost doubled in size, flip it out onto the kitchen counter with the seam-side facing down. Using your hands or a bench scraper, gently shape the mass of dough into a tight ball. This preshape step will create surface tension across the top of the dough and make it easier to shape the dough into an oval shape later. Let the dough rest for 30 minutes on the counter, uncovered.

Now, lightly dust an oval-shaped banneton basket with rice flour or whole wheat flour. This will prevent the dough from sticking to the basket while it proofs. Shape the dough once more into a tight ball. Dust dough with flour as well.

Finally, flip the dough upside down into your prepared banneton basket. The seam-side should be facing up.

Move the banneton basket to your refrigerator to let it cold-proof in the fridge overnight. I usually leave my dough proofing in the fridge until I’m ready to bake it the next day. 8-24 hours is a good amount of cold-proofing time for this recipe.

The next day, 30 minutes before you want to bake your bread, preheat your oven to 500°F with a Dutch oven. When the oven has preheated, take the dough out of the fridge. You can score and bake the loaf cold from the fridge; there is no need to let it come up to room temperature.

Flip the dough out of the banneton basket onto a piece of parchment paper that is a little bit larger than the size of the dough. Dust off any excess flour from the top of the dough. Score and transfer to Dutch oven.

Bake for 20 minutes at 500°F with the lid closed. 20 minutes later, remove the lid and continue baking at 500°F for 12-15 minutes, until the top of the loaf has a golden brown color. Move the bread to a wire rack to cool for at least one hour before slicing.