NOTE: This recipe requires levain (aka the starter), which, if you don’t have a baker friend to give you some, you’ll need to make your own. Johnson’s Sourdough Basics workshop is a hands-on place to start, but if you want to try it at home, he recommends the starter recipe and instructions provided on theperfectloaf.com.
216 g. (60%) bread flour
120 g. (33%) whole wheat flour
25 g. (7%) soft flour (rye, buckwheat, corn, etc.)
270 g. (75%) water
108 g. (30%) levain
8 g. (2.2%) salt
Mix flours, water, and levain together in a bowl. Sprinkle salt on top of dough. Let sit 20 minutes to an hour.
Mix the salt into the dough completely, using your hand to squeeze everything together. When fully incorporated, let sit 20 minutes.
Using wet hands, fold the dough over itself, working your way around the bowl in a circle. Do this twice around the bowl and let rest 30 more minutes.
Repeat this same step four more times (totaling five folds in all), letting the dough rest 30 minutes in between these intervals. After the final fold, let the dough rest for an additional 45 minutes, or for an hour or two in the fridge.
On a floured surface, turn the dough out onto the table. Just like the folding technique, bring each part of the dough up toward the center. When a ball is formed, invert this so the seam is facing down, and let rest 30 minutes.
To shape dough, add a small amount of flour to the table, invert your dough so that the seam faces up, and bring both the left and right side of the dough up and toward the center, so they connect in the middle. Roll this new shape downward, starting at the top of the dough, until you have a log with a seam at the bottom. Cover the smooth top with flour and place in a proofing basket (you can also line a metal or plastic colander with a linen dish towel). Proof for about three hours at room temperature, or overnight in the fridge.
Bake at 500°F for 15 minutes with steam (ideally), and another 20 to 30 minutes at 475°F without steam.