When your starter has doubled in size and it’s ready to use, add the following ingredients to a large mixing bowl: the water, salt, and sourdough starter. Stir the liquid ingredients together with a spoon to break up the starter and to dissolve the salt.

Next, add all of the bread flour to the mixing bowl and stir the ingredients together until a rough dough forms. At this point, cover up the bowl with a kitchen towel and let the dough rest for 30 minutes.

After the 30 minute rest, uncover the dough and add the 25 grams of olive oil right on top of the dough. Squeeze the oil into the dough with your hands until it is thoroughly combined with the dough and the dough starts to hold together again.

Immediately after squeezing in the oil, give the dough it’s first set of stretch and folds. Grab an edge of the dough and stretch it upwards, then when the dough begins to resist, fold it over the top of the dough. Continue stretching and folding the edges of the dough about 10-20 times total, or until the dough starts to resist your stretching and to firm up. After that, cover the dough up again and let it rest for 30 minutes.

Give the dough a second set of stretch and folds. The dough should be smoother and hold together better than it did during the first set of stretch and folds. Cover the dough and let it rest for another 30 minutes.

Finally, give the dough one last set of stretch and folds. Immediately flip the dough over so that the smooth side is facing up and the seam side is facing down.

Cover the mixing bowl with a layer of plastic wrap (or move the dough to a glass bowl with an airtight lid) and then let the dough rise at room temperature overnight, or for at least 6-8 hours. You want the dough to completely double in size overnight, which usually takes about 6-7 hours for me, but can take longer if your kitchen temperature is col. The next morning, your dough should be doubled in size and ready to shape.

Prepare a 9×13″ non-stick, metal cake pan by greasing it with 25 grams of olive oil. This will create an additional non-stick layer between the dough and the pan, but it will also give the sourdough focaccia its traditional fried-bottom texture and flavor.

Turn out the risen dough into the oiled pan. Move the dough around carefully to get oil on both sides of the dough, and then flip the dough over so that the smooth side is facing up and the seam side is facing down.

Gently pull on the edges of the dough to stretch it into a rectangular shape to match the pan. The dough likely won’t be able to stretch all the way to the edges of the pan at this point, but as long as it is rectangular, it will rise and fill up the pan during the final proof.

Cover the pan with a layer of plastic wrap, or a lid, if your pan has one, and let the dough rise for 3-5 hours at room temperature. The dough should puff up and fill the pan during this time. Be sure to give the focaccia dough enough time to proof and fill the pan; even if it takes 6-8 hours, that’s OK.

Pre-heat your oven to 450°F (232°C) 30 minutes before you’re ready to bake. There is no need to add steam to your oven for this recipe. If you have a baking steel or pizza stone in your oven, feel free to use it, but you can also place the pan directly on the oven rack to bake.

Uncover the risen focaccia dough and top it with 25 grams of olive oil. Wet your fingertips in the oil and dimple the top of the dough by pressing down all over the dough with your fingertips. (Don’t press through the dough to puncture it, but just press down gently until you feel the bottom of the pan.) Dimpling the dough will create bumps, ridges, and bubbles throughout the dough where oil and toppings can collect, creating pockets of flavor throughout the sourdough focaccia.

After dimpling the dough, add your desired toppings. A few sprinkles of salt and a few teaspoons of dried rosemary is my favorite topping combination.

To bake, slide the pan of dough onto your middle oven rack or onto the pizza stone in your oven. Bake the focaccia for 30-35 minutes at 450°F (232°C).

Remove the focaccia from the oven when it is golden brown and slide it out of the non-stick cake pan and onto a wire rack. Let the focaccia cool for at least 30 minutes before slicing.

Slice the focaccia into strips, or into sandwich-style slices for a delicious sandwich.