01 - In a large mixing bowl, combine the sourdough starter, water, and brown sugar. Stir until completely dissolved.
02 - Add bread flour, whole wheat flour, cinnamon, nutmeg, ginger, and salt. Mix until a sticky dough forms.
03 - Fold in the grated carrots, raisins, and nuts until evenly distributed throughout the dough.
04 - Knead the dough gently for 3-4 minutes, either by hand or with a dough hook, until just combined.
05 - Cover the bowl with a towel and let rest for 30 minutes to allow flour hydration.
06 - Perform 3-4 sets of stretch and folds every 30 minutes over the next 2 hours to develop gluten structure.
07 - Cover and let the dough rise at room temperature for 4-6 hours, until doubled in size.
08 - Shape the dough into a boule or batard, then place in a parchment-lined banneton or bowl.
09 - Cover and refrigerate overnight (8-10 hours) for a slow ferment and enhanced flavor development.
10 - Preheat the oven to 450°F with a Dutch oven inside for optimal heat retention.
11 - Turn the dough onto parchment, sprinkle with oats and seeds if desired, and score the top with a sharp knife.
12 - Carefully transfer the dough into the preheated Dutch oven. Bake covered for 25 minutes to create steam.
13 - Uncover and bake for 20 more minutes, until golden brown and crusty with internal temperature reaching 200°F.
14 - Cool completely on a wire rack for at least 2 hours before slicing to preserve texture.