Rosemary Thyme Cheddar Seeded Sourdough Batard

Steps

1. Evening before mixing (about 8 pm): feed your starter from your own supply with equal weights of all-purpose flour and water (separate from the amounts in this recipe) and leave it at about 75°F (24°C); it should double and peak in 8 to 12 hours, by morning.
2. Morning: in a large bowl, mix the all-purpose flour, the rye flour and 330 g (all but 20 g) of the water until no dry patches remain. Cover and rest 45 minutes (autolyse).
3. Add the starter to the dough and squeeze it in by hand until fully combined, about 3 minutes.
4. Sprinkle the salt over the dough with the remaining 20 g of water and pinch it in until absorbed. This dough is about 70% hydration and 2% salt.
5. In a small bowl, stir together the flaxseed, half of the sesame seeds, the rosemary and the thyme. Cover the dough and rest 30 minutes.
6. Bulk rise 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; on the first set, spread the seed-and-herb mixture over the dough and fold it in; on the second set, scatter the cheddar cubes over the dough and fold them in.
7. After the folds, leave the dough covered until it has grown about 50%, looks domed and airy, and jiggles when the bowl is shaken.
8. Turn the dough onto a clean, dry counter, pre-shape into a loose round and rest 20 minutes uncovered.
9. Shape into a tight batard. Dust a towel-lined oval basket with the cornmeal, mist the top of the loaf lightly with water, press it into the remaining half of the sesame seeds, and set it seam side up in the basket.
10. Cover and proof 1 hour at room temperature, then refrigerate overnight, 12 to 16 hours, for the cold proof.
11. Next day: place a Dutch oven with its lid in the oven and preheat to 475°F (245°C) for 45 minutes.
12. Turn the cold loaf onto parchment, score one long slash, and lower it into the hot Dutch oven. Cover and bake 20 minutes.
13. Uncover, reduce to 450°F (230°C) and bake 25 to 30 minutes more, until the crust is deep mahogany brown and the center reads 205°F (96°C).
14. Cool the loaf on a rack at least 2 hours before cutting into 12 slices.