Onion and Rosemary Focaccia
We spent one gray, cold and very poor winter living in Philadelphia, in a teensy apartment that looked down over an alley through which early morning garbage trucks rumbled our wake-up call. Our weekly visit to Metropolitan Bakery was one of our few indulgences. Set on a picturesque corner south of Rittenhouse Square, the bakery felt so cosmopolitan, so civilized, and oh, how we looked forward to sharing a crumbly millet muffin and a giant square of perfectly oily focaccia. Funny how we look back on those months, which felt so grinding and directionless at the time, with such fondness now. In any case, that focaccia still satisfies a deep spot of hunger, and this version is a classic, elemental, perfect combination. The addition of boiled potato yields a remarkably light and tender dough. We sometimes add a red onion to the mix, just for the splash of color.
— Kate & Guy, Onions Etcetera The Essential Allium Cookbook
For the dough
1 small russet potato
2-1/2 cups cold water
5 cups all-purpose flour
2-1/2 teaspoons active dry yeast
1 teaspoon sugar
2 tablespoons olive oil, plus more for oiling the pan
For the topping
1 small sprig fresh rosemary
2 small sweet onions, thinly sliced
3 tablespoons olive oil
3/4 teaspoon flaky sea salt
To make the dough, peel the potato and cut into 1-inch cubes. Combine the potato and 2½ cups cold water in a small saucepan, cover and bring to a boil. Boil the potato until very tender when pierced with the tip of a knife, about 15 minutes. Use a handheld or regular blender to purée the potatoes and cooking liquid to a smooth slurry (alternately, run the mixture through a food mill or mash with a fork until as smooth as possible). Let cool until just warm (the water should not be boiling hot when added to the yeast).
Meanwhile, whisk together the flour, yeast, sugar and 1½ teaspoons salt in a large bowl. Add the olive oil and the warm potato mixture and stir until the dough just comes together (it will be very soft and sticky). Generously oil a large bowl and transfer the dough to it, rolling the dough around to coat it in the oil. Cover tightly with plastic wrap and set aside at room temperature to rise until doubled in size, about 3 hours.
Strip the rosemary leaves and coarsely chop them. Combine the rosemary, onions and olive oil in a bowl and toss together.
Heat the oven to 400°F. Lightly oil a half-sheet pan, then scrape the dough onto the pan. With lightly oiled fingers, stretch and pull the dough to fill the pan. Press your fingertips into the dough to create deep dimples. Scatter the onion mixture evenly over the dough, drizzling any remaining oil over everything. Sprinkle the sea salt over the topping. Cover the pan with a clean kitchen towel and let rise until the dough is almost level with the sides of the pan, about 1 hour.
Bake the focaccia until golden brown, 30 to 35 minutes. Remove from the oven and let cool a few minutes before cutting into big squares.
Serves 8 to 10
Excerpted from Onions Etcetera by Kate Winslow and Guy Ambrosino. Copyright © 2017 Burgess Lea Press. Photography copyright © 2017 Guy Ambrosino. Published by Burgess Lea Press, an imprint of The Quarto Group. Reproduced by arrangement with the Publisher. All rights reserved.