320 g Flour
340 g Water
1/4 tsp. Instant Yeast
565 g of the above Poolish
340 g Flour
170 g Water
15 g Salt
1 1/2 tsp. Instant Yeast
85 g Olive Oil
Fresh, coarsely chopped Rosemary and Olive Oil, as needed
Kosher Salt, to taste
Prepare the poolish the night before baking by stirring together the flour, yeast and water until the ingredients in the bowl are well incorporated. Cover the bowl with plastic wrap and let sit at room temperature until the poolish becomes bubbly, about 3 hours. Immediately place the bowl in the refrigerator and let the poolish ferment there overnight.
The next morning, remove the poolish from the refrigerator and let warm to room temperature for 1 hour. Add the water and poolish to the bowl of a stand mixer and mix on low speed with the whisk attachment until the mixture is homogeneous. With the whisk still going, add the olive oil and continue mixing until the oil is incorporated. Switch to the paddle attachment, add the flour, yeast and salt, and mix on low speed until all the flour is hydrated, about 2-3 minutes. Increase the speed to medium and mix until low to medium gluten development is achieved, about 5 minutes.
Scrape the extremely fluid dough into an oiled container and let rest for 5 minutes. Fold the dough, using wet hands to prevent sticking.
Let the dough ferment for 1 1/2 hours at room temperature, repeating the dough folding at 30 and 60 minutes. After this first fermentation period, the dough is transferred to an oiled baking sheet and olive oil is brushed onto the surface of the dough. Using fingertips, the dough is then gently eased to the edges of the baking sheet, trying to maintain an even thickness throughout. If the dough becomes too elastic during this step, let the dough rest for 5 minutes, then resume. Sprinkle the surface of the dough with fresh, coarsely chopped rosemary, lightly cover with plastic wrap, and let ferment a second time for 1 1/2 hours. After this time, sprinkle additional olive oil over the surface of the dough, dimple the surface with fingertips, and sprinkle the surface with kosher salt, to taste.
The focaccia is baked in a pre-heated, 450°F oven for 20 minutes, rotating the pan 180° after the first 10 minutes to ensure even baking. The pan is removed from the oven and the focaccia is removed immediately from the pan and allowed to cool on a cooling rack for at least 20 minutes before cutting into slices.