makes one loaf; Timing wise, I usually begin autolyse between noon and 2pm so that the bread is ready to bake first thing the following morning.
Using a mixer with dough hook, combine the flours and water. Cover bowl and allow to rest 1 hour.
Add starter to dough and mix with hook until combined. This begins 3–4 hours of "bulk" fermentation.
After 1 hour rest, mix in the salt using the dough hook for 5–10 minutes. Cover bowl and allow to ferment for remaining time with stretch-and-folds every 30 minutes as it fits your schedule. (I've made perfectly tasty loaves with no stretch-and-folds, but when you can do it, the bread's texture will improve.)
Using a bench scraper, pull and tuck dough around and under the dough ball, shaping it with your hand and the bench scraper in the other hand until you form a taught, jiggly ball. If it's not somewhat jiggly, ferment a little longer before shaping. Let rest while you prepare the banneton/proofing basket.
Line the banneton with a linen liner then dust with flour.
Turn the dough ball upside down and pull the edges towards the center starting with noon and 6-o'clock, then 9 and 3-o'clock. Stitch the seam together by pinching dough from one side and stretching it to the other side, alternating about 3 or 4 times down the length of the seam. Transfer the dough lump, keeping seam side up, into the banneton. Cover (with plastic or a slightly moistened lint-free kitchen towel) and allow to proof at room temperature for 1.5–2 hours and then into the refrigerator for a cold proof overnight, maximum of 10–12 hours or dough will become overly sour.
Alternatively, you can bake the dough same-day. To do this, proof at room temperature for 2–4 hours and then proceed with baking.
Place covered Dutch-oven into oven (rack lowered just under middle so that covered baker fits) and preheat to 475°F.
Tear a piece of parchment paper large enough to cradle your bread dough into the baking pot, about 15-inches. Get your spray bottle with fresh water ready, flour for dusting, and your lame.
When oven has preheated, carefully remove the covered pot from the oven.
Remove dough from refrigerator and invert onto the parchment paper. Spritz with water, dust with flour, and score lengthwise with the lame. Immediately transfer to the pot by using the parchment as a cradle and lowering it into the hot pot. Return the lid and place back in the oven. Bake for 30 minutes at 475°F (lower to 450°F if you have convection); remove lid and bake for 15 minutes longer. Immediately transfer dough to a rack to cool so that the bottom doesn't get too dark.