01 -
In a large bowl, whisk together the flour, salt, and instant yeast. Add the water. Using a rubber spatula, mix until the liquid is absorbed and the ingredients form a sticky dough ball. Lightly coat the surface of the dough with olive oil. Cover the bowl with a damp towel, cloth cover, or plastic wrap. Place in the refrigerator for at least 12 hours or up to three days.
02 -
Line two 8- or 9-inch pie plates or a 9×13-inch pan with parchment paper or grease with butter. Coat the pans with 1 tablespoon of oil each or 2 tablespoons for a 9×13-inch pan.
03 -
Using two forks, deflate the dough by pulling it toward the center from the sides of the bowl. Split the dough into two equal pieces or leave whole if using a 9×13-inch pan. Place the dough into the prepared pans. Roll the dough in the oil to coat and let it rest for 3 to 4 hours at room temperature.
04 -
Set a rack in the middle of the oven and preheat to 425°F.
05 -
If using rosemary, sprinkle it over the dough. Pour 1 tablespoon of oil over each round of dough (or 2 tablespoons for a 9×13-inch pan). Using your fingers, create deep dimples in the dough. Sprinkle with flaky sea salt.
06 -
Transfer the pans to the oven and bake for 25 to 30 minutes, until the underside is golden and crisp. Transfer the focaccia to a cooling rack and cool for 10 minutes before cutting and serving.
07 -
Once cooled completely, store in an airtight container at room temperature for up to 3 days, or freeze for up to 3 months. Reheat at 350°F for 15 minutes to refresh the crust.