Before making the dough, be sure to feed your sourdough starter (perhaps twice) and allow it to reach peak activity level.
Make an autolyse by combining the flour and almost all of the water in a bowl until thoroughly mixed. Let it sit covered at room temperature (70-75 degrees is optimal) for about an hour.
After the autolyse has rested, mix in the called-for active sourdough starter, salt, and remaining water until thoroughly combined. Mixing with your hands is normal and acceptable.
Optional: Lift the dough ball (which may be quite loose) out of bowl and on a clean counter use the “slap and fold” technique to tighten the dough.
Once finished, put the dough back in the bowl and allow to rest at room temperature for 30 minutes. Cover the bowl with a tea towel or similar. This begins the "bulk fermentation" time.
After 30 minutes, start the first round of “stretch and fold” - gently lifting up on one side of the dough and folding it back over itself. Give the bowl a quarter turn and continue to stretch and fold the dough until it is taught and resists pulling. Avoid tearing the dough. Use wet hands to prevent sticking. Cover the bowl again, and let sit.
Repeat the stretch and fold process every 30 minutes for a total of 3 or 4 rounds.
After about 4 hours of bulk fermentation at room temperature, stretch and fold the dough one final time to help it tighten up.
Next, set the dough on a lightly floured surface and shape the loaf into a similar shape as your banneton (proofing basket - e.g. a round loaf, or long oval loaf). Let the dough “bench rest” for a final 10 minutes.
After the final bench rest, place the dough in a flour-dusted (and potentially cloth-lined) banneton proofing basket of choice. Cover with a breathable towel, and place in the refrigerator to proof for 8 to 16 hours. We usually do this overnight.
After cold-proofing in the refrigerator, preheat the oven to 475 to 500 degrees F. (Experiment to see what temperature works best for your oven). If you’re using a dutch oven or combo cooker, place it in the oven to preheat for one hour.
After an hour of preheating, quickly and carefully transfer the cold dough (straight from the fridge) out of the banneton and into the hot combo cooker or dutch oven. Line the combo cooker or dutch oven with parchment paper first. Score the top of the loaf with a bread lame if desired. (See Note 1 below)
Bake the loaf covered for 35 minutes, and then remove the lid and bake for an additional 7 to 10 minutes uncovered. (See Note 2 and Note 3 below)
Once done, immediately remove the finished sourdough loaf from the oven and combo cooker and place the loaf on a wire rack to cool.
Let the sourdough bread loaf sit at room temperature for several hours before cutting. The steam trapped inside is important moisture to retain!