Combine the flours, salt and yeast in a large bowl. Add the water and stir all the ingredients together. The dough should be shaggy and a little sticky - you shouldn't really be able to pick this dough up or handle it.

Cover the bowl and let the dough rest in room temperature for 12 to 18 hours. The longer you let it sit, the more flavor is developed. After 18 hours, the dough should be bubbly on top and a shade darker than it was when you started.

Place a piece of parchment paper on the countertop and dust very generously with flour. Wet your hands and fold the dough over on itself a few times to release the air inside the dough. (Wetting your hands will help prevent the dough from sticking to you.) Turn the dough out onto the floured parchment paper, seam side down.

Dust more flour on the top of the dough and cover the dough by inverting the mixing bowl over the top. (Alternately, you could use a clean kitchen towel to cover the dough, but I find this often sticks to the dough, ruining both the appearance of the bread and the towel.) Let the dough rest like this for up to 2 hours. After the dough has rested for 1 to 1 ½ hours on the countertop, place a lidded cast iron Dutch oven into your oven and pre-heat the oven to 425ºF for 30 minutes.

Then, working carefully, remove the Dutch oven from the oven and take off the lid. Remove the bowl and slide your hand underneath the dough ball. Making sure you don't touch the hot cast iron pot, invert the dough into the pot as gently as you can. Cover with the lid. If this seems too much for you, use the parchment paper to lift the dough into the pot, paper and all, and cover. Return the pot to the oven for 30 minutes.

After 30 minutes, remove the lid from the Dutch oven and let the bread continue to bake until it is nicely browned on top - about 10 to 20 minutes. Remove the pot from the oven and let the bread sit in it for about 5 minutes. Then, transfer the beautiful loaf to a cooling rack to cool. Although it is tempting to dive right in, let the bread cool for 30 minutes before enjoying.