1. Combine Starter and Water: In a large mixing bowl, gently whisk together your active sourdough starter and the warm water until the starter is mostly dissolved and the mixture is milky. This ensures your starter is well-distributed.

2. Mix Dry Ingredients and Form Dough: Add the bread flour and salt to the starter mixture. If using, also add the granulated sugar. Mix with a wooden spoon or your hands until a shaggy dough forms and no dry flour remains. Cover the bowl with a damp cloth or plastic wrap and let it rest for 30 minutes (this is called autolyse, which helps gluten develop).

3. Incorporate Cranberries and Orange Zest: After the rest, turn the dough out onto a lightly floured surface. Gently flatten it into a rough rectangle. Sprinkle the dried cranberries and orange zest evenly over the dough. Fold the dough over itself several times, gently kneading for about 2-3 minutes to distribute the inclusions without tearing the dough too much.

4. Bulk Fermentation with Folds: Return the dough to the clean bowl. Over the next 2-3 hours, perform a series of “stretch and folds.” Every 30-45 minutes, gently grab a portion of the dough from the edge, stretch it upwards, and fold it over the center. Rotate the bowl and repeat 3-4 times until all sides have been folded. This builds strength in the dough. After these folds, let the dough continue to bulk ferment at room temperature until it has visibly increased in size (about 30-50%) and looks bubbly, typically 4-8 hours total from when you first mixed.

5. Shape the Loaf and Cold Proof: Gently turn the dough out onto a lightly floured surface. Shape it into a round or oval loaf, creating tension on the surface. Place the shaped dough seam-side up into a floured banneton or a bowl lined with a floured tea towel. Cover and refrigerate for 8-12 hours, or up to 24 hours. This cold proof develops flavor and makes the dough easier to handle.

6. Preheat Oven and Bake: About 45 minutes before baking, place a Dutch oven with its lid into your oven and preheat to 450F (230C). Once preheated, carefully remove the hot Dutch oven. Gently invert the cold dough into the hot Dutch oven. Score the top of the dough with a sharp knife or razor blade (a simple cross or a single slash works well). Cover with the lid and bake for 30 minutes.

7. Final Bake and Cool: Remove the lid from the Dutch oven and continue baking for another 15-20 minutes, or until the crust is deeply golden brown and sounds hollow when tapped on the bottom. Carefully remove the loaf from the Dutch oven and transfer it to a wire rack to cool completely for at least 1-2 hours before slicing. Slicing too early can result in a gummy texture.