Gather the ingredients so that you have everything close at hand on the counter or table.
Make the Dough
In a large bowl, combine the "fed" or active sourdough starter, warm water, extra-virgin olive oil, artisan sea salt, granulated sugar, dried minced onion, garlic powder, and 2 cups of all-purpose flour. Mix together by hand with a wooden spoon or dough whisk until combined.
Continue mixing in the remaining all-purpose flour until the dough comes together in a ball. The dough may still be sticky at this point. Cover with plastic wrap and allow the dough to set out on the counter overnight.
The next morning, turn the dough onto a lightly floured surface and stretch and fold two or three times until it comes together in a nice ball.
Place the dough in a greased bowl and cover with plastic wrap. Refrigerate for at least 10-12 hours, or up to 4-5 days.
Allow Dough to Rise
When you're ready to make the Focaccia, remove the dough from the refrigerator and bring to room temperature.
Drizzle 1-2 tablespoons of extra-virgin olive oil in a 9"x 9" square pan. Place the dough in the pan and gently stretch and pull the edges to fill the entire pan. Cover with plastic wrap and allow to rise for 2-4 hours, depending on the temperature of your kitchen.
If you prefer a thinner focaccia, you may place the dough in an oblong baking pan. Continue with the remaining instructions, allowing less baking time for the thinner dough.
Prepare the Focaccia
Preheat oven to 425F degrees, and allow the oven to heat for at least 60 minutes before baking.
When the dough has doubled, gently press down with your fingers to dimple the dough, nearly to the bottom of the pan.
Drizzle the dough with extra-virgin olive oil and sprinkle with Fleur De Sel sea salt. If desired, you may also sprinkle with fresh or dried rosemary, sliced black or green olives, and sun-dried tomatoes.
Bake in preheated oven for 25-30 minutes until light golden brown. Remove from oven and allow to cool for a few minutes before serving.
To serve, turn bread out onto a cutting board. Slice into rectangles or squares and place on a plate or platter.
Freeze Leftovers
You may freeze any leftovers by wrapping bread in aluminum foil and placing in a freezer bag. To reheat, place foil-wrapped frozen bread on a baking tray and heat at 350 degrees until warmed through, about 10-12 minutes.
This recipe will serve 12-16 people.
Notes
* This bread is best served warm or at room temperature on the same day it is baked.