You can mix this dough by hand or use a stand mixer. In the bowl of a stand mixer equipped with a dough hook, combine both flours, water, salt, and the ripe sourdough starter, reserving the olive oil for later. Start mixing on low speed (speed 1) for 1 to 2 minutes until everything is just combined. Increase the speed to medium (speed 2) and mix for another 5 minutes until the dough becomes stronger and gathers around the hook. Allow the dough to rest in the bowl for 10 minutes. Turn the mixer back on to speed 1 and gradually add the olive oil while mixing. Once the olive oil is fully incorporated, increase to speed 2 for an additional 1 to 2 minutes until the dough is cohesive again. Transfer the dough to a container for bulk fermentation and cover it.

Perform 4 sets of stretch and folds at 30-minute intervals, starting 30 minutes after the bulk fermentation begins.

Generously oil the inside of a 9×13" rectangular pan or two 10" round baking pans. Gently transfer the dough from the bulk fermentation container directly into the oiled pan(s). If using two round pans, divide the dough on a work surface before placing it in the pans. The dough will proof in the pan(s) for 4 hours. During the first hour, every 30 minutes, uncover the pan and gently stretch the dough with wet hands toward the edges to help it fill the pan. The dough will naturally expand over the proofing period, so minimal spreading is required. After the first hour, cover the pan and let the dough proof for the remaining 3 hours. About 30 minutes before the proofing period ends, preheat your oven to 450°F (230°C) with a rack positioned in the lower third.

Once your oven is preheated, use wet fingers to dimple the surface of the dough all over. Generously drizzle olive oil over the top, ensuring it is well covered. Sprinkle with chopped herbs and coarse sea salt. Bake the focaccia for about 30 minutes, or until it is golden brown on both the top and bottom. Let it cool in the pan for a few minutes before transferring it to a cooling rack. This focaccia is delightful straight from the oven and is best enjoyed on the day it is baked.