Prepare the levain 6 to 8 hours before mixing the dough. Mix together high-protein wheat flour, water, and mature starter. Let it ferment until it reaches peak activity.

Place potatoes in a steamer basket over 1–2 inches of water. Cover and steam for 30 minutes or until tender. Peel while warm, then chill in the fridge.

Combine high-protein wheat flour, all-purpose flour, and water in a stand mixer. Mix for 2 minutes until fully hydrated. Let rest until the levain is ready.

Add the levain to the dough. Mix on low for 3 minutes, then increase speed to medium-high for 5–8 minutes. The dough should be smooth and elastic. Add salt and mix for another 2 minutes.

Place dough in a proofing box. Let it bulk ferment at 75–80°F (23–26°C) for 4 hours.

After 1 hour, laminate the dough on a damp surface, adding cubed potatoes, piquillo peppers, Manchego, and oregano. Perform two additional coil folds at 1-hour intervals.

Divide dough into two portions. Preshape into rounds and rest for 45 minutes–1 hour.

Shape into batards (long oval loaves) and place in floured bannetons, seam-side up.

Refrigerate for 12–16 hours at 39°F (4°C) for the final cold proof.

Preheat your Dutch oven to 500°F (260°C). Place parchment paper in the pot and transfer the proofed loaf. Score the top and bake with the lid on at 500°F for 5 minutes.Lower the temperature to 480°F (248°C) and bake for 10 minutes. Remove the lid, reduce to 450°F (232°C), and bake for another 15–20 minutes until golden brown.

Let the bread cool on a wire rack for at least 30 minutes before slicing. Enjoy warm for the best cheesy experience!