1. Combine Starter and Water: In a large mixing bowl, gently combine the active sourdough starter with the warm water. Use a Danish dough whisk or your hand to break up the starter until it’s mostly dissolved in the water. The mixture should look milky and slightly frothy.

2. Mix in Flour and Salt: Add the bread flour and fine sea salt to the bowl. Mix with your hand until all the flour is hydrated and no dry spots remain. The dough will be shaggy and sticky. Cover the bowl with a damp kitchen towel or plastic wrap and let it rest for 30 minutes (this is called autolyse, which helps the flour absorb water).

3. Incorporate Seeds and Perform Stretch and Folds: After the rest, sprinkle the mixed seeds over the dough. Begin the first set of “stretch and folds.” With wet hands, grab a portion of the dough from one side, stretch it upwards, and fold it over to the opposite side of the bowl. Rotate the bowl a quarter turn and repeat. Do this 4-6 times until the dough feels slightly stronger. Cover and let rest for 30 minutes. Repeat this stretch and fold process 3-4 more times over the next 2-3 hours, incorporating the seeds evenly and building dough strength.

4. Bulk Fermentation: After the final set of stretch and folds, cover the bowl and let the dough ferment at room temperature for 2-4 more hours, or until it has increased in volume by about 30-50% and looks bubbly. The exact time will depend on your room temperature and starter’s activity.

5. Shape the Dough: Gently turn the dough out onto a lightly floured surface. Shape it into a round or oval. If desired, lightly mist the top of the dough with water and sprinkle with extra seeds for topping, pressing them gently to adhere. Carefully transfer the shaped dough, seam-side up, into a floured banneton basket or a bowl lined with a floured kitchen towel.

6. Cold Proofing: Cover the banneton with plastic wrap or a shower cap and place it in the refrigerator for 8-12 hours, or even up to 24 hours. This cold proofing slows down fermentation, develops flavor, and makes the dough easier to handle.

7. Preheat Oven and Dutch Oven: About an hour before baking, place your Dutch oven (with its lid) into your oven and preheat to 450F (230C). This ensures the Dutch oven is scorching hot, which is crucial for a good crust.

8. Bake the Bread: Carefully remove the hot Dutch oven from the oven. Gently invert the cold dough from the banneton into the hot Dutch oven. Score the top of the dough with a sharp knife or a bread lame (a single slash or a simple pattern works well). Cover with the lid and bake for 30 minutes. Remove the lid and continue to bake for another 10-15 minutes, or until the crust is deeply golden brown and the internal temperature reaches 200-210F (93-99C).

9. Cool Completely: Carefully remove the bread from the Dutch oven and transfer it to a wire rack. Let it cool completely for at least 1-2 hours before slicing. This allows the internal structure to set and prevents a gummy texture.