In a large bowl, whisk together the flour, salt, baking powder, and instant yeast. Add the water.
Using a rubber spatula, mix until the liquid is absorbed and the ingredients form a sticky dough ball.
Rub the surface of the dough lightly with olive oil.
Cover the bowl with a cloth or plastic wrap and place it in the refrigerator for at least 12 hours or up to three days.
Using damp hands or two forks, deflate the dough by releasing it from the sides of the bowl and pulling it toward the center. Rotate the bowl in quarter turns as you deflate, turning the mass into a rough ball.
Let the dough rest for 3 to 4 hours.
Lightly oil a standard bread loaf pan. Pour the focaccia dough into the pan.
With damp hands, gently dimple the focaccia all over with your fingers. Don't create too many dimples or bubbles. Sprinkle on salt.
Place the pan in a preheated oven at 425ºF for 20 minutes. Reduce heat to 375ºF and bake for 20 to 25 minutes more or until golden all around.
Let it rest for 10 minutes before cutting. Enjoy!
