Adapted from Samin Nostrat, author of Salt, Fat, Acid, Heat; this salty, moist fermented flat bread is sure to please!
For the dough:
100 grams (~1/3 cup) active sourdough starter
550 grams (2 cups) lukewarm water (filtered or de-chlorinated)
750 grams (5 cups) bread flour or all-purpose flour
18 grams (1 tbsp) fine sea salt
50 grams (¼ cup) extra-virgin olive oil, plus more for pan and finishing
Coarse salt for finishing
For the brine:
5 grams (1 tsp) fine sea salt
80 grams (⅓ cup) lukewarm water (filtered or de-chlorinated)
In a large bowl, mix the active (ie, fed within the last 6-8 hours) sourdough starter into the water. Once mostly dissolved, mix in the flour and olive oil. Stir until just incorporated and scrape the sides of the bowl clean and cover with a moist towel. After 30 mins, distribute the salt for the dough on top and fold it into the dough by gently stretching and turning the dough. Do this one more time after 30-60 minutes. Leave the dough to ferment at room temperature for 12 - 14 hours until it has doubled in volume.
Spread 2 to 3 tablespoons oil evenly onto an 18-by-13 inch (46-by-33 cm) rimmed baking sheet. When dough is ready, pour out onto pan. Pour an additional 2 tablespoons of olive oil over the dough and gently spread it across. Gently stretch the dough to the edge of the sheet by placing your hands underneath and pulling outward. The dough will shrink a bit, so repeat stretching once or twice over the course of 30 minutes to ensure dough remains stretched.
Dimple the dough by pressing the pads of your first three fingers in at an angle. Make the brine by stirring together salt and water until salt is dissolved. Pour the brine over the dough to fill dimples. Proof focaccia for 45 minutes until the dough is light and bubbly.
Preheat oven to 450°F and place a baking stone on middle rack in oven. Allow the stone to preheat with the oven before proceeding with baking. Sprinkle focaccia with flaky salt. Bake for 25 to 30 minutes directly on top of stone until bottom crust is crisp and golden brown when checked with a metal spatula. To finish browning top crust, place focaccia on upper rack and bake for 5 to 7 minutes more.
Remove from oven and brush or douse with 2 to 3 tablespoons olive oil over the whole surface (don’t worry if the oil pools in pockets, it will absorb as it sits). Let cool for 5 minutes, then release focaccia from pan with metal spatula and transfer to a cooling rack to cool completely. Serve warm or at room temperature.