12 hours before you plan to mix this dough feed your sourdough starter according to the instructions provided above
Once your starter is ripe, which means doubled in size, measure out all the ingredients in separate containers
In a bowl mix: flours, water, leaven, salt. Mix until there are no lumps and all the flour has been incorporated
Perform folds every 30 minutes for the next 3-4 hours (depending in your dough's temperature)
Cover and let the dough sit in the refrigerator for the next 12 to 36 hours.
Bring the dough out of the refrigerator, divide in half. Place the other half back in the refrigerator covered.
Grease your baking pan with olive oil and place one of the doughs inside. Stretch it out until it covers the pan in about 80%. If it fights you back during the process, let it rest and extend as it slowly.
Cover the baking pan and let it rise again. For the 1 or 2 more hours (depending on your doughs temperature)
Preheat your oven to 450°F
Dimple the focaccia and add olive oil on top. At this moment add the vegetables of your choice. For the one you see on the photo I added: thyme, swiss cheese, onions, green olives.
Bake for 35-40 min. It's ready when the bottom of the focaccia is gold and crispy.
Enjoy!
Repeat the same process with your 2nd half of dough.