Mix together in a large bowl:
400 gm bread flour (I use 300-350 gm white, 100-50 gm whole wheat)
8-9 gm salt
¼ t dry yeast
(optional 2 T mixed seeds)
Add:
300 ml water
Stir the water into the dry ingredients and form into a sticky ball.
Put a plate or something on top of the bowl, and set aside (in a warm room, if possible) for 18-24 hours. If you want to leave it for longer, put it in the fridge for a little while to slow down the rising.
Cut a piece of parchment paper and place it on a clean surface. I use a plastic placement on a tray. Sprinkle a little flour on the parchment so the dough won't stick. I spread the flour with a rubber spatula, then use the spatula to scrape the edges of the dough to loosen it from the bowl and make it easy to pick it up.
Next, as if the dough were a square, pull one side up and over, then another side up and over, then another, then another. Finally, pick up the gooey mass and turn it over, smooth side up. Put a big bowl over it (or a cloth, if you prefer), and let it rise for 1.5-2 hours.
This is how the dough looks before rising:
When the dough has risen, preheat the oven and baking pan. See the risen dough below:
Place a Dutch oven, donabe, or other oven-safe covered pot into the oven and preheat to 230ºC (450ºF). When preheated, carefully remove the pot from the oven, take off the lid, and slide or lift the risen dough into the hot pot. Put the lid back on, and put the pot on a low shelf in the oven.
Dough placed in the hot donabe pot:
Bake for 48 minutes at 230ºC (450ºF). Remove from oven. If you are not sure it's done, you can check the internal temperature with a thermometer. It should be at least 96ºC (205ºF).
Cool on a rack before cutting.