SOURDOUGH BREAD

Steps:

• For the sourdough feeder: Eight to 15 hours before mixing the levain, feed your starter by mixing the bread flour, water and old sourdough starter together in a medium bowl until smooth. Transfer to a storage container with a lid.
• For the levain: Mix the bread flour, water and ripe sourdough starter together with your hands in a medium bowl until smooth. Cover with plastic wrap or a damp towel and allow to rest at room temperature for about 12 hours. The levain will be very dense and sticky.
• For the dough: Mix the water, levain, bread flour, whole wheat flour and salt with your hands in a large bowl until smooth and well combined. It will be slightly tacky. Transfer to another bowl that's been lightly coated in nonstick spray. Cover with plastic wrap or a damp towel and allow to rise at room temperature until roughly 1 1/2 times its size, about 1 hour.
• Working in the bowl, stretch and fold the dough over itself on its 4 sides, and flip to seam-side down. Cover and allow to rest for about 30 minutes. Repeat this process 3 more times (for a total of 4 stretching, folding and resting turns). At this point, the dough should feel soft and pillowy, and spring back to the touch of your finger.
• To give the boule its final shape, start seam-side up. Grab the top portion of your dough (as if it were a "corner"), pull and fold into the center. Repeat with the remaining 3 corners of the dough. Flip it over and while pushing down, rotate in a circle bringing the dough towards and away from you. This creates tension and seals the bottom. It should be tight and spring back to your touch.
• Line a large bowl with a clean kitchen towel, then dust generously with bread flour. Place the boule seam-side up in the prepared bowl and allow to rise at room temperature until about 1 1/2 times its volume, about 1 1/2 hours.
• Cover and allow to rest in the refrigerator for at least 2 hours and up to 24 hours.
• Place a large Dutch oven in the oven and preheat to 500 degrees F. Place a piece of parchment paper flat on the counter.
• Flip the boule onto the parchment, seam-side down, and dust with flour. Using a serrated knife (or a baker's lame), score the top of the boule as desired. Carefully remove the Dutch oven from the oven and transfer the boule on the parchment into the Dutch oven, using the edges of the parchment to lift.
• Bake, covered, for 25 minutes. Remove the lid and continue to bake until the boule is dark brown, about 20 minutes more. Transfer to a wire rack and cool completely.