Rosemary Walnut Whole Wheat Sourdough Batard

Steps

1. Day 1, 8 am: feed your starter its usual equal-weight feeding and leave it at about 75°F (24°C); it should double and peak in 4 to 6 hours, domed and bubbly. This feeding is separate from the ingredients listed here.
2. While the starter rises, heat the oven to 350°F (175°C), toast the walnuts on a baking sheet for 8 to 10 minutes until fragrant, cool, then chop roughly. Turn the oven off.
3. Set aside 10 g of the whole wheat flour for dusting; the remaining 390 g goes into the dough. Set aside 30 g of the water; the remaining 360 g goes in now.
4. About 1 pm (when the starter peaks): in a large bowl, stir the 390 g of whole wheat flour, the bread flour and the 360 g of water until no dry patches remain. Cover and rest 45 minutes (autolyse).
5. Add the starter, honey and olive oil to the dough and squeeze them in with wet hands for 2 minutes.
6. Sprinkle the salt over the dough, pour on the reserved 30 g of water, and squeeze and fold until absorbed and the dough feels cohesive.
7. Bulk rise at about 75°F (24°C) for 4 to 5 hours. After the first 30 minutes, spread the dough out, scatter the walnuts and rosemary over it, and fold to enclose; this counts as the first stretch-and-fold.
8. Do 3 more sets of stretch-and-folds 30 minutes apart, then leave the dough covered. Bulk is done when it has risen about 50%, looks domed and airy, and jiggles when the bowl is shaken. The dough is about 80% hydration and 2% salt, counting the starter's share.
9. Dust the counter with half of the reserved 10 g of whole wheat flour, turn out the dough, pre-shape into a loose round, and rest 20 minutes.
10. Dust a towel-lined bowl or banneton with the remaining half of the reserved whole wheat flour. Shape the dough into a tight batard and place it seam-side up in the bowl.
11. Cover and cold proof in the fridge overnight, 12 to 14 hours.
12. Day 2: place a Dutch oven with its lid in the oven and preheat to 475°F (245°C) for 45 minutes.
13. Turn the cold dough onto parchment, score it lengthwise down the center, and lower it into the hot Dutch oven. Bake covered for 20 minutes.
14. Remove the lid, lower the heat to 450°F (230°C), and bake 25 to 30 minutes more until the crust is deep mahogany and the center reads 205°F (96°C).
15. Cool the loaf on a rack for at least 2 hours before slicing into 12 slices.