Preparation

1. To make the starter, place all the starter ingredients in a medium-size bowl, and whisk until well combined. The mixture will be thick and shapeless. Cover and set the bowl aside in a warm, draft-free location to rise until more than doubled in size (about an hour).

2. Once the starter has finished rising, make the dough. In the bowl of your stand mixer, place the flour, salt, cream of tartar, and sugar, and use a hand held whisk to combine. Add the water, oil, and risen starter, and mix on low speed with the dough hook until combined. Raise the mixer speed to medium and knead for about 5 minutes. When you raise the dough hook, a trail of dough from the hook to the bowl should be intact for at least the count of five. The dough will be quite sticky. Spray a silicone spatula lightly with cooking oil spray, and scrape down the sides of the bowl. Transfer the dough to a lightly oiled bowl or proofing bucket large enough for the dough to rise to double its size, and cover with an oiled piece of plastic wrap (or the oiled top to your proofing bucket). Place the dough in the refrigerator for at least 24 hours and up to 5 days.

3. On baking day, line a large rimmed baking sheet with unbleached parchment paper and set it aside. In a small bowl, combine the topping ingredients and mix to combine to create an herb oil. Set the bowl aside.

4. Remove the dough from the refrigerator, scatter a generous amount of flour on a flat surface, scrape the dough out of the bowl on top of the flour, and sprinkle with flour. Turn the dough over on itself with a bench scraper and transfer it carefully, with the help of a floured bench scraper, to the center of the prepared baking sheet. Drizzle half of the herb oil on top of the dough and, with the tips of your fingers, press and push the dough out toward the edges of the pan. The dough will be very wet and may be difficult to handle. Cover the dough with oiled plastic wrap and place in a warm, draft-free location to rise until doubled in size (about 2 hours). The dough will rise both up and out.

5. About 25 minutes before the end of the dough’s rise, preheat your oven to 232°C (450°F) and place a pizza stone on the lower rack. Once the dough has finished rising, pour the remaining herb oil over the top of the risen dough. Gently spread the oil around with your fingertips, dimpling the dough if you see any large bubbles, but otherwise taking care not to deflate it.

6. Place the baking sheet on the pizza stone, and bake for 5 minutes at 232°C (450°F). Lower the oven temperature to 204°C (400°F) and continue to bake for another 15 minutes, or until the top of the focaccia is golden brown and the center of the bread reaches 93° C (200°F) on an instant-read thermometer. Slice and serve warm.