Sourdough Bread

Take the starter out of the fridge and stir in the water and flour.

Cover and leave at room temperature for about 4 hours, until it has doubled and is just starting to fall.

Weigh the bread flour and whole wheat flour into the bowl and mix with the spatula.

Add the water and mix until all the flour is moistened and the dough is shaggy. Don't overwork it.

Cover with the bag and rest for at least 1 hour 30 minutes, until the starter is ready.

Add the starter to the dough. Feed what's left of the starter and put it back in the fridge (see Notes).

Fold and mix for 2–3 minutes, until combined. The dough will be very sticky.

Cover and rest for 30 minutes.

Sprinkle half the salt over the dough. With wet fingers, lift one edge of the dough, stretch it up and fold it over to the other side. Sprinkle on the rest of the salt, then stretch and fold again.

Repeat the stretch and fold 4–5 more times, turning the bowl each time.

Lift the dough, drop it back in, fold it over and press, as if kneading, for 2–3 minutes, until the salt is worked in.

Cover and rest for 1 hour. Bulk fermentation has started, so keep the dough at about 23°C75°F. In a cool kitchen, put it in the oven (turned off) with a bowl of just-boiled water.

With wet fingers, stretch and fold the dough 6–7 times, until it tightens and no longer stretches easily. Let it fall gently onto itself, without pressing out the air.

Cover and rest for 45 minutes.

Repeat steps 1 and 2 three more times, for four rounds in all, but rest for 1 hour after the last round. The dough gets lighter, puffier and less sticky each time, with bubbles by the last round.

It's ready when it has grown to 1.5–2 times its original size and feels light. If unsure, do one more round and give it another hour.

Lightly flour the counter and let the dough slide out of the bowl on its own, so it doesn't deflate.

With floured hands, pull the far side of the dough away from you slightly and fold it to the center. Loosen it with a floured scraper if it sticks.

Stretch the right side out slightly and fold it to the middle, then do the same with the left side.

Roll the dough away from you from the near edge, pulling back slightly to keep tension on the surface. Slide the scraper under the dough to tighten it into an oval or round.

Sprinkle the seeds over the top, or dust it with flour if not using seeds.

Dust the banneton with the all-purpose flour. Slide the scraper under the dough and lift it into the basket upside down, seed side down.

Cover the basket with the bag and proof at room temperature, ideally 23°C75°F, for 1 hour 30 minutes.

Poke the dough with a floured finger. If it springs all the way back, give it more time. If it springs back a little and leaves a dent, it's ready.

Refrigerate the dough, still covered, for 8–14 hours.

Put the Dutch oven, lid on, on a rack in the middle of the oven and heat to 230°C450°F. Give it at least 30 minutes, even after the oven says it's ready, so the pot heats through.

Meanwhile, cut a square of parchment big enough to lift the loaf by, and crease its edges so it lies flat. Crumple a square of foil slightly and fold it in half.

When the pot is hot, take the dough out of the fridge. It should go into the oven cold.

Turn the loaf out onto the parchment, seed side up, lifting the basket straight off.

With the razor blade, cut four shallow slits around the lower sides of the loaf. Then cut one deep slit along the top, about 1 cm1/2 in deep, stopping 2.5 cm1 in from each end.

Take the pot out, remove the lid and put the foil in the bottom. Lower the loaf in by the parchment. If the top slit has closed, cut it again.

Cover and bake for 35 minutes. Uncover and bake for 10 minutes more, or 15 minutes for a darker crust.

Lift the loaf out by the parchment onto a rack. Cool for at least 30 minutes, ideally 2 hours or longer, before slicing. It keeps cooking as it cools, and cutting it early makes it gummy.