Yield: One 1 1⁄2-pound sourdough boule
1 cup leaven, or fed sourdough starter
2 cups lukewarm water
5 cups flour, plus up to 1 cup more for the work surface
1 1⁄2 tsp salt
1. Feed your starter by setting aside half of it and feeding the remainder with 4 ounces of flour and 4 ounces of lukewarm water. Stir to combine, and set the starter aside for 8 to 12 hours to complete the culture proof before you use it to bake.
2. In a mixing bowl, pour 1 cup fed sourdough starter into 1 cup lukewarm water. Add 3 cups flour, a little at a time. Stir until loosely combined, then mix thoroughly with wet hands. Cover the container loosely and set aside for a half-hour if using white flour, or 45 minutes for whole-grain flour.
Feed the set-aside starter with 4 ounces each of flour and lukewarm water. Stir to combine, cover loosely, and leave at room temperature until it becomes fully active. This is your new starter to maintain and use.
3. After the dough’s autolyse period (about 20 minutes for white flour, and as much as 40 for whole-grain flour), sprinkle the salt over the dough and mix it in using your hands. If the dough feels dry, add a little more water — it should be somewhat sticky. Turn the dough out onto a floured board and knead it for a couple of minutes, until it no longer picks up any new flour. Return it to the container, cover loosely and leave at room temperature to undergo bulk fermentation.
4. Bulk fermentation usually lasts 3 to 4 hours. During the first couple of hours, gently stretch and fold the dough about every half-hour, pulling one edge at a time up and over the center, until all sides have been stretched. After the first few times, be extra-gentle, and take care to keep the built-up gases inside the dough.
5. Turn the dough out onto a floured board and let it rest for 10 to 20 minutes. If it seems very strong and cohesive at this point, take care not to overwork it when shaping the dough. If it seems slack and tears as you stretch, you may want to give it extra stretching folds before the final shaping. If it is extremely slack, incorporate more flour as you fold and shape, although ideally you would not incorporate any more flour at this point.
6. Pat the dough lightly into a rectangle. Pick up each side one at a time, gently stretch it out, and fold it back over the dough’s center, until all four sides have been stretched. Leave the dough alone for a minute to relax.
7. Roll the dough into a ball, or “boule.” Pull gently but tightly to ensure that the top is taut all the way around. One way to do this is to put the ball on an unfloured surface and begin spinning it gently. The bottom will grab the work surface and create tension as you rotate the ball. Another way is to grab and gently pull four “corners” to the bottom and pinch them together.
8. Let the shaped dough rise for its final proof, right-side-up, on a floured baker’s peel. You can improvise a baker’s peel by flouring the back of a cookie sheet. Or, let the dough rise upside down in a floured proofing basket, or “banneton,” which will help it keep its structure. You can improvise one by lining a mixing bowl with a floured cotton towel.
The dough should proof 2 to 4 hours at room temperature. Dust a bit of flour on the surface, and cover it with a kitchen towel to keep a crust from forming.
9. Preheat the oven to 500 degrees Fahrenheit about 30 minutes before baking, with a Dutch oven, cloche or enclosed pan in the oven.
After 30 minutes, carefully remove the lid, and use the baker’s peel to shuttle the loaf into the pan (or turn the loaf upside down from the proofing basket or bowl into the pan).
Replace the lid, turn the oven down to 450 degrees, and bake the bread for 20 minutes. Then, remove the lid and allow the loaf to bake for 20 to 25 minutes more, uncovered, for good browning.
10. Remove the finished bread to a cooling rack. Let the loaf cool for at least one hour. Proper cooling is important to keep moisture from escaping and for the bread’s final crust development.