Combine the flour, yeast, and salt in a large bowl. Pour in the water and stir with a spoon. Once you have most of the flour incorporated, use your hands to finish mixing the dough. Note: the dough will be wet and sticky.
Cover the bowl with plastic wrap and set it in a quiet place the kitchen for 10-12 hours.
Once you are ready to shape the dough, pull out your cast iron skillet. Take 2 tablespoons of the olive oil and pour it into the skillet. Get your hands oiled and scrape the dough out of the bowl into the skillet.
Turn the dough around in the skillet to coat it with oil, then gently spread the dough out so that it fills the skillet. If it won't spread out all the way to the edges, wait 10 minutes and push it out some more.
Cover the skillet with plastic wrap and let the dough rest for 1 hour.
When the dough has rested for 30 minutes, begin heating the oven. Move the oven rack to the lower middle position and heat the oven to 500F.
Once the dough is done resting, prep it for baking. Dimple the dough with your fingertips. Scatter the olives over and work them down into the dough. Then scatter the sage over and press some of that into the dough.
Drizzle over the final 2 tablespoons of olive oil and sprinkle with coarse salt.
Bake until cooked through and golden brown, 15-20 minutes in a 12-inch skillet. 20-25 in a 10-inch skillet.
Remove the skillet from the oven. Transfer the bread to a cooling rack and cool to room temperature.