Oat Porridge Rye Sourdough Batard

Steps

1. Morning of day 1 (about 8 a.m.): refresh the sourdough starter with its usual feeding (equal weights of feed and water) and leave it at about 75°F (24°C); it should double and peak, domed and bubbly, in 4 to 6 hours.
2. Right after feeding, make the oat soaker: pour the boiling portion of the water (120 g) over the soaker portion of the oats (80 g), stir, cover and let cool to room temperature. Set the crust portion of the oats (20 g) aside.
3. When the sourdough starter peaks (about 1 p.m.), stir the lukewarm portion of the water (280 g) with the honey and the sourdough starter in a large bowl until milky.
4. Add the rye flour, the bread flour and the salt to the starter mixture and mix until no dry patches remain. Fold in the oat soaker until evenly spread through the dough. The dough is about 82% hydration and 2% salt (counting the starter) and will feel sticky, as rye doughs do.
5. Bulk rise, covered, at about 75°F (24°C) for about 4 hours. During the first 90 minutes, do 3 sets of stretch-and-folds 30 minutes apart with wet hands, then leave the dough alone. It's ready when it has grown by about half, looks puffy and shows bubbles at the sides.
6. Turn the dough onto a lightly wet counter and, with wet hands, shape it into a tight batard. Mist or brush the top with water and roll it in the reserved crust oats.
7. Place the loaf oat side down in a parchment-lined banneton or bowl, cover and cold proof in the fridge for 12 to 14 hours overnight. It's ready when a wet fingertip poke springs back slowly.
8. Day 2: place a Dutch oven with its lid in the oven and preheat to 475°F (245°C) for 45 minutes.
9. Lift the loaf out on its parchment so the oat-crusted side is up, score it lengthwise and lower it into the hot Dutch oven. Bake covered for 20 minutes.
10. Remove the lid, reduce to 450°F (230°C) and bake 25 to 30 minutes more, until the crust is deep brown and crisp and the center reads 205°F (96°C).
11. Cool the bread on a rack at least 3 hours so the rye crumb sets before slicing into 12 slices.