In a large bowl, combine the flour, salt and yeast. Add the water. With a fork, stir until the flour is completely moistened, but the dough is not entirely smooth. Cover and let rest for 12 to 15 hours at room temperature.
With a wet hand, keeping the dough inside the bowl, stretch and fold the dough over itself 6 times, turning the bowl 90 degrees with each fold. Gradually add the cheese between each fold. Cover and let rest for 30 minutes.
Line a 17 x 12-inch (43 x 30 cm) baking sheet with a strip of parchment paper, letting it hang over two sides.
Pour the oil onto the baking sheet. Spread the dough out on the baking sheet with your fingertips, turning it over a few times to coat well in the oil. Do not worry if the dough is not the same size as the baking sheet at this point. Cover with plastic wrap directly on the surface of the dough. Let rest for 2 hours 30 minutes at room temperature or until the dough rises to the top of the baking sheet.
With the rack in the middle position, preheat the oven to 425°F (220°C).
With lightly oiled hands, make small wells in the dough with your fingertips, pressing the dough out to the same size as the baking sheet. Bubbles should appear in the dough.
Bake for 25 to 30 minutes or until the focaccia is nicely browned. Let cool on a wire rack.
Note from Ricardo
Although the focaccia is best enjoyed the same day it is made, it will keep for 3 days in an airtight container at room temperature. Once baked, the focaccia can be frozen.
