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slab of sourdough potato focaccia topped with garlic cloves and cooking on a silver cooling rack
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5 from 1 vote

Sourdough-Potato Focaccia

Servings: 16 pieces

Ingredients

For the leaven

  • 3 tablespoons all-purpose flour
  • 3 tablespoons whole wheat flour
  • 3 generous tablespoons warm water
  • 1 tablespoon active starter

For the dough

  • ¾ cup mashed cooked yellow or red potatoes about two medium potatoes
  • cups warm tap water or potato cooking water about 85°F
  • cups all-purpose flour
  • teaspoon coarse salt
  • 1 tablespoon honey omit if vegan
  • 3 tablespoons olive oil, divided
  • butter, to grease the pan see Note

Optional toppings to choose from

  • 12 kalamata olives
  • 12 small garlic cloves, peeled
  • cherry tomatoes
  • half a shallot, sliced thinly
  • Bell pepper strips
  • fresh herbs

Instructions

Day One, 9 am: Make the leaven and cook the potatoes

  • Between 6 and 12 hours before you make the focaccia dough, combine the flours, water, and active starter in a jar or nonreactive bowl, mix well, cover with a lid or plate, and set aside at room temperature.
  • Cut the potatoes into 1- to 2-inch cubes. Place in a small pot, cover will water, bring to a boil and reduce to a vigorous simmer until a fork easily slides into the potatoes, about 10 minutes. Strain and reserve the cooking water to add to the dough, if desired. Run the cooked potatoes through a food mill or mash with a fork until smooth.

Day One, 4 pm: Make the dough

  • In a medium, nonreactive bowl, combine the warm water and mashed potatoes. Mix well with a whisk or fork until combined well.
  • Add flour, salt, honey, 1 tablespoon of olive oil, and the leaven. Stir with a fork, dough whisk or your clean hand until you have a consistent dough. It will be very wet and very shaggy. Cover the bowl with a thin cloth or plate. Note the time. This is the beginning of the bulk fermentation, which will last approximately 3½ to 4 hours, depending on the temperature in your kitchen.
  • After 30 minutes, do the first set of stretches and folds of the dough. With a wet hand, reach underneath the bottom of the dough, pull the dough up, and fold it over onto itself. Turn the bowl a quarter turn and repeat the stretching and folding. Repeat two more times, for a total of four turns.
  • Repeat this four-turn stretching and folding about once an hour during the bulk fermentation. By the end of the bulk fermentation, the dough will be smooth, glossy, elastic, and filled with air.

Day One, 8 pm

  • Near the end of the bulk fermentation, generously grease a 9 by 13-inch metal cake pan or glass baking dish with butter. Pour in 1 tablespoon of the olive oil and spread it evenly around the bottom.
  • At the end of the bulk fermentation, turn the dough out onto a clean surface. Wet your hands and pull gently on the top and sides of the dough to form an 8-inch square. Fold the square like a letter, in three sections, folding the left side onto the middle and then the right side over that. You now have a rectangle. Fold the bottom of the rectangle onto the middle and then the top over that. Avoid squeezing out the air bubbles as you work. Place the dough in the pan, seam side up. Turn the dough seam-side down to both conceal the seam and coat the dough in oil. Gently stretch the dough toward the corners of the pan. It won’t fill the pan at this point. Cover with a towel or an inverted baking pan and refrigerate overnight, or for at least 8 hours and up to 16 hours.

Day Two, 8 am

  • Remove the pan from the refrigerator. Gently stretch the dough toward the corners of the pan to form a rectangle. The dough will still not fill the pan. Cover the pan and let it sit at room temperature until the dough has puffed up, 2 to 2½ hours. At that point, it should nearly fill the pan. It will not quite double in size.
  • Twenty minutes before the end of proofing, preheat the oven to 425°F. Just before baking, drizzle the remaining 1 tablespoon olive oil over the dough and slather it across the top with your hand. Gently press your fingers into the dough to dimple it, carefully stretching the dough toward the edges of the pan to fill it evenly. Try not to deflate the dough. If desired, place toppings such as kalamata olives, garlic cloves and very small cherry tomatoes into the dimples, or lay slices of shallots, bell pepper strips or fresh herbs across the top. Sprinkle with coarse salt.

Day Two, 10:30 am

  • Bake at 425°F for 25 to 35 minutes, or until the focaccia is golden brown. Cool on a rack for 10 minutes, then remove from the pan. Cool another 10 minutes before slicing.

Notes

The ample amounts of olive oil in this recipe will not prevent the bottom of the focaccia from sticking to the pan unless you use a nonstick pan like this one. Butter maintains a barrier between the dough and the pan during proofing, which olive oil does not. Vegan butter will also work in place of butter.