Olive Oil Walnut Olive Sourdough Batard

Steps

1. Day 1, 8 am: feed your sourdough starter on its usual schedule and leave it at about 75°F (24°C). It should double and peak, domed and bubbly, in 4 to 6 hours.
2. While the starter rises, toast the walnuts in a dry skillet over medium heat for 4 to 5 minutes until fragrant, cool, and chop roughly. Pat the olives dry and halve them.
3. About 1 hour before the starter peaks, mix the bread flour and whole wheat flour with 320 g of the water (keep the other 20 g back) until no dry patches remain. Cover and rest 45 minutes (autolyse).
4. Add the sourdough starter to the dough and squeeze it in with wet hands. Sprinkle on the salt, add the reserved 20 g of water and 15 g of the olive oil (keep 5 g for the bowl), and squeeze and fold for 3 to 4 minutes until smooth and fully absorbed. This is about 71% hydration and 1.8% salt.
5. Rub the bowl with the remaining 5 g of olive oil and turn the dough into it. Bulk rise at about 75°F (24°C) for 4 to 5 hours in total.
6. After 30 minutes, do the first set of stretch-and-folds: spread the dough a little, scatter over the walnuts, olives and oregano, then lift each side up and over the middle, turning the bowl, until the add-ins are tucked in.
7. Do 3 more sets of stretch-and-folds, 30 minutes apart, then leave the dough undisturbed. Bulk is done when it has grown about 50%, looks domed, jiggles and shows bubbles at the sides.
8. Turn the dough onto a clean counter, pre-shape it into a loose round with damp hands and rest 20 minutes. Flip it and shape into a tight batard by folding in the sides and rolling it up toward you.
9. Place the batard seam side down on a sheet of parchment set inside an oval basket or bowl, cover, and cold proof in the fridge for 12 to 14 hours overnight.
10. Day 2: put a Dutch oven with its lid in the oven and preheat to 500°F (260°C) for 45 minutes.
11. Lift the cold batard out on its parchment, score one long, shallow slash at an angle, and lower it into the hot Dutch oven. Cover, reduce to 475°F (245°C) and bake 20 minutes.
12. Remove the lid, lower to 450°F (230°C) and bake 20 to 25 minutes more, until the crust is deep brown and crisp and the center reads 205°F (96°C).
13. Cool the loaf on a rack for at least 2 hours before slicing into 12 slices, so the crumb sets and the crust stays crisp.