In a large mixing bowl, combine the flours, yeast, salt, and mix with a fork to blend.
Add 1 ¼ Cups (10 ounces) of cool water and mix it in with the fork.
The dough should be wet, but not soggy. If the dough seems dry or all flour is not incorporated, add water 1 Tb. at a time until dough is uniformly wet.
Cover the bowl loosely with plastic wrap, and leave at room temperature for 12 to 24 hours.
About 1 hour before you want to bake the bread, sprinkle a dry cutting board or counter liberally with flour. Also spread out a lint-free kitchen towel on the counter, and sprinkle generously with a circle of flour.
Use a rubber spatula to scoop the dough onto the floured board. Use your hands to pull each side of the dough up and pinch them all together on top at the center of the dough, like a drawstring pouch.
Pick up the dough and place it pouch-side down on the floured towel. Loosely fold the sides of the kitchen towel up over the dough, and let it rest for at least 30 minutes, preferably 1 hour.
30 minutes before you want to bake, pre-heat your oven to 475 degrees.
If your cast iron pot has a lid with a plastic handle, REMOVE IT and stop up the hole with a rolled-up piece of aluminum foil. The handles can melt (and smoke and smell…) at high oven temperatures.
Place your pot with a lid into the oven to pre-heat as well.
After 30 minutes, use potholders to remove the pot from the oven, take off the lid, and carefully invert the towel to dump the dough into the pot. Sprinkle the dough with coarse sea salt if you like (it helps create a delicious crust), use potholders to replace the lid and put the pot into the oven.
Turn the oven down to 450 degrees and bake for 55 minutes, until golden and crusty, and somewhat hollow-sounding when thumped.
Remove the pot from the oven and turn the bread out onto a rack to cool.
Wait as long as you can (the experts say at least 1 hour) before cutting into it, for the best-textured loaf. But really, sometimes I can only wait 5 minutes, and it tastes so great hot out of the oven with a smear of butter!