1. Combine Wet Ingredients and Starter: In a large mixing bowl, gently whisk together the active sourdough starter, warm water, and honey (or maple syrup) until well combined. The mixture should look milky and slightly bubbly.

2. Add Dry Ingredients: To the wet mixture, add the bread flour, whole wheat flour, and fine sea salt. Mix with a sturdy spoon or your hands until a shaggy dough forms and no dry streaks of flour remain. Avoid overmixing at this stage.

3. Incorporate the Seeds: Sprinkle in the flax seeds, chia seeds, sesame seeds, and poppy seeds. Gently fold them into the dough until they are evenly distributed. The dough will be sticky.

4. First Rise (Bulk Fermentation): Cover the bowl with a damp kitchen towel or plastic wrap. Let the dough rise at room temperature (ideally 70-75F) for 8-12 hours, or until it has visibly doubled in size and appears bubbly. This long, slow rise develops flavor.

5. Shape the Loaf: Lightly flour your work surface. Gently turn the dough out onto the floured surface. Using floured hands, gently stretch and fold the edges of the dough towards the center, forming a round or oval shape. Avoid deflating the dough too much.

6. Second Rise (Proofing): Lightly oil a proofing basket (banneton) or a bowl lined with a floured kitchen towel. Carefully transfer the shaped dough, seam-side up, into the prepared basket/bowl. Cover again and let it rise for another 2-4 hours at room temperature, or until it looks puffy and springs back slowly when gently poked.

7. Preheat Oven and Dutch Oven: About 30 minutes before baking, place a Dutch oven with its lid into your oven and preheat to 450F (230C). Heating the Dutch oven ensures a crispy crust.

8. Bake the Loaf: Carefully remove the hot Dutch oven from the oven. Gently invert the proofed dough into the hot Dutch oven. If desired, score the top of the dough with a sharp knife or razor blade. Cover with the lid and bake for 30 minutes. Remove the lid and continue baking for another 15-20 minutes, or until the crust is deep 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 step is crucial for the crumb to set and for the best texture and flavor.