Step 1

Levain (or sourdough starter) – 9:00 p.m. (the night before baking)The night before baking, mix the levain ingredients in a jar and leave them covered overnight. Instead of making a levain, you can also feed your sourdough starter and use it in the morning instead.

Step 2

Roast two large russet potatoes in the oven at 350°F (175°C) for about 1 hour until a knife is easily inserted. Then, peel and rice (or mash). Set aside until mixing.

Step 3

To the bowl of a stand mixer with hook attachment, add the flour, water, salt, and ripe levain. Mix on low speed for 2 to 3 minutes until the ingredients come together. Next, mix on medium speed (2 to 3 on a KitchenAid) for 4 to 5 minutes. Let the dough rest for 10 minutes, covered. Turn the mixer on low speed and mix for 2 to 4 minutes until the dough gains more strength and begins to cling once again to the dough hook. Next, with the mixer running, slowly pour in the olive oil. Continue to mix until all the oil is added and the dough comes back together. Next, add the riced potato and mix on low speed for 1 to 2 minutes until the potato disappears into the dough. Transfer the dough to a bulk fermentation container and cover.

Step 4

Give this dough three sets of stretches and folds at 30-minute intervals.

Step 5

Divide – 12:00 p.m.Liberally grease two 10-inch round baking pans or one 9×13-inch rectangular pan. Scrape dough out of bulk container and, using wet hands, divide the dough into two for the two pans (or place directly into large pans). Gently stretch the dough out to fill the pan, stopping when resistance is felt. Cover.

Step 6

Set a timer for 30 minutes and perform gentle stretching as previously done. Repeat this stretching one more time after 30 minutes. After the second set of stretches, cover the pans and let the dough rest for the remaining time in proof, about 2 hours more.

Step 7

Top and bake – 3:15 p.m.Preheat home oven or wood-fired oven to 425°F (220°C). Top focaccia with any desired toppings. Bake for 30 minutes, rotating pan halfway through this time.