Add the starter to the water and mix well. (Optimum timing is to use the starter the day after it has been fed or to use it the same day of feeding right after it’s begun to deflate after reaching its maximum growth.) Add the flours to the starter-water mixture and mix to combine thoroughly. Cover and let sit at room temperature for 2 hours (autolyze).

Sprinkle the salt over the top of the dough and, using a wet hand, poke the salt into the dough and mix the dough thoroughly for 1 minute. Transfer the dough to a large bowl that has been oiled with the olive oil. Turn to coat the dough with the oil, cover with plastic wrap, and set aside. Keep a water bowl and a dough scraper handy. Set a timer for 30 minutes and when it goes off, pull and stretch the imagined 4 corners of the dough (imagine a north, south, east and west orientation) up and into the middle of the dough. Once you have stretched the 4 “corners” up and into the middle, turn the dough over so that the folds are now on the bottom. Cover with the plastic wrap again and repeat this process again after another 30 minutes 3 more times, for a total of 4 dough-folds in a 2 hour period. Cover the dough and allow to rest at room temperature for 2 hours longer. Transfer the bowl to the refrigerator and allow to rest, refrigerated, at least overnight and up to 30 hours. The sour flavor will intensify the longer the dough is retarded in the refrigerator. 

When you are ready to cook the bread, remove the dough from the refrigerator and allow to come to room temperature for 1 hour. (Note:  remove the plastic wrap and cover with a kitchen towel so that any condensation doesn’t fall onto the dough.) 

Working carefully, loosen the dough from the sides of the bowl (a dough scraper comes in handy for this), trying to disturb the dough as little as possible, and transfer to a well-oiled baking dish, stretching the dough lightly to roughly the shape of the dish. Cover again and allow the dough to relax for 1 to 2 hours – it will continue to relax into the shape of the baking dish and will continue to grow in size. Do not allow the dough to overproof. If room temperature is very warm, this will affect the timing, so pay attention to your baking conditions. 

Preheat the oven to 425 degrees F.  

Drizzle the top of the dough with extra virgin olive oil and use your fingers to make sure it is evenly coated. Sprinkle with any desired toppings, then dimple the dough every 2 inches using a firm touch with a finger.  Sprinkle the top of the dough with flaky salt and transfer to the oven. If your oven has a convection feature, turn it on now. Cook until the bread is puffed, deeply golden, and a thermometer inserted into the center reads 210 degrees F, usually 18 to 20 minutes. Remove the bread from the oven and, using two spatulas, transfer the bread from the pan to a wire rack until completely cool.