1. Combine Wet Ingredients: In a large mixing bowl, gently whisk together the active sourdough starter, warm water, honey, and olive oil until well combined. The mixture should look slightly milky and have a pleasant, sweet aroma.

2. Add Dry Ingredients: To the wet mixture, add the whole wheat flour, all-purpose flour, rolled oats, and salt. Use a wooden spoon or your hands to mix until all the flour is hydrated and a shaggy dough forms. It will be sticky at this stage.

3. Knead the Dough: Turn the dough out onto a lightly floured surface. Knead for 8-10 minutes until the dough becomes smoother and more elastic. It should pass the “windowpane test” – if you can stretch a small piece of dough thin enough to see light through it without tearing, it’s ready.

4. First Rise (Bulk Fermentation): Place the kneaded dough into a lightly oiled bowl, turning once to coat. Cover the bowl with plastic wrap or a damp kitchen towel and let it rise in a warm spot for 4-6 hours. The dough should visibly increase in size, becoming about 50-75% larger and feel airy.

5. Shape the Loaf: Gently turn the dough out onto a lightly floured surface. Shape it into a round or oval loaf. For a round loaf, gently pull the edges of the dough towards the center, then flip it over and cup your hands around it, rotating to create surface tension.

6. Second Rise (Proofing): Place the shaped loaf into a floured banneton basket or a bowl lined with a floured kitchen towel, seam-side up. Cover and let it proof at room temperature for 1-2 hours, or refrigerate overnight for a deeper flavor development and easier handling. The dough should feel puffy and spring back slowly when gently poked.

7. Preheat Oven and Bake: About 30 minutes before baking, place a Dutch oven or a baking stone with a lid in your oven and preheat to 450 F (232 C). Carefully remove the hot Dutch oven, invert the dough into it (or onto the baking stone), score the top with a sharp knife or razor blade, and sprinkle with extra rolled oats.

8. Bake the Bread: Bake with the lid on for 30 minutes, then remove the lid and continue baking for another 10-15 minutes, or until the crust is deeply golden brown and the internal temperature reaches 200-210 F (93-99 C). Let the bread cool completely on a wire rack before slicing to ensure the best texture.