Mix poolish ingredients into a container with a loose lid. Mix water and yeast first, let sit for about 30 seconds, add flour, then mix thoroughly.

Let poolish sit for 16 to 24 hours. (If you're in a rush, the absolute minimum is 4 hours.)

Put water, yeast, and poolish in a large bowl and mix until soupy.

Add flours and salt to large bowl and mix with spoon until you're no longer able to.

With an extremely wet hand, squish, mix, and turn the dough for 90 seconds.

Cover bowl with plastic wrap and let sit for 30 minutes.

After 30 minutes, stretch and fold/slap and fold your dough for 2 to 3 minutes.

Cover bowl with plastic wrap and let sit for 30 more minutes.

Slap and fold/stretch and fold for another 2 to 3 minutes. Form into ball in bowl and cover with plastic wrap. Let sit 60 minutes.

Dump dough out onto well floured surface. Form into loaf and place seem side up into floured proofing basket.

Preheat Dutch oven to 480-500° for 40 minutes.

Throw dough into Dutch over, score the loaf, then bake with lid on for 18 minutes, then lid off for 25 to 30 minutes at 480°F.