Feta Walnut Dill Whole Wheat Sourdough Batard

Steps

1. Morning, day 1 (about 8 a.m.): feed your sourdough starter equal weights of whole-wheat flour and water from your own starter supply (not from this recipe's amounts) and leave it at about 75°F (24°C). It should peak, doubled and bubbly with a domed top, 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 them, and chop. Crumble the feta, pat it dry with a paper towel and chill it. Chop the dill.
3. Weigh out 10 g of the bread flour and set it aside for dusting.
4. About 1 hour before the starter peaks, mix the whole-wheat flour and the remaining 110 g of bread flour with 350 g of the water until no dry patches remain. Cover and rest for 1 hour.
5. Add the peaked sourdough starter to the dough and squeeze and fold it in by hand for 2 to 3 minutes. Rest 20 minutes.
6. Sprinkle the salt over the dough with the remaining 30 g of water and squeeze it in until the water is absorbed and the dough feels smooth again. The formula is about 76% hydration and 1.6% salt; the feta adds more salt.
7. Bulk rise, covered, at about 75°F (24°C) for 4 to 5 hours. During the first 2 hours, do 4 sets of stretch-and-folds 30 minutes apart, lifting each side of the dough and folding it over itself.
8. At the second set of stretch-and-folds, spread the dough out a little in the bowl, scatter over the walnuts, feta and dill, and fold them in gently so the feta stays in chunks. Do the last 2 sets as usual.
9. Bulk is done when the dough has grown about 50%, looks domed with bubbles at the edges and jiggles when the bowl is shaken.
10. Dust the counter with half of the reserved bread flour, turn the dough onto it, pre-shape it into a loose round and rest 20 minutes. Shape it into a tight oval batard, tucking in any feta that pokes out.
11. Dust a basket or towel-lined bowl with the remaining half of the reserved bread flour and place the batard in it seam side up.
12. Cover and cold proof in the fridge overnight, 12 to 14 hours. The loaf is ready when a fingertip pressed into it leaves a dent that springs back slowly.
13. Day 2: put a Dutch oven with its lid in the oven and preheat to 475°F (245°C) for 45 minutes.
14. Turn the cold loaf onto parchment, score it with one long, shallow slash, and lower it into the hot Dutch oven. Cover and bake 20 minutes.
15. Uncover, reduce the oven to 450°F (230°C) and bake 22 to 25 minutes more, until the crust is deep brown and crisp and the center reads 205°F (96°C).
16. Cool the bread on a rack for at least 2 hours before slicing into 12 slices, so the crumb sets and the crust stays crisp.