Sweet Potato, Red Onion and Fontina Tart

Crust

¾ cup walnuts

1¼ cups whole wheat pastry flour

1¼ cups all-purpose flour, plus more for dusting

2 tablespoons chopped fresh thyme and/or rosemary

¾ teaspoon salt

¾ teaspoon freshly ground black pepper

½ cup extra virgin olive oil

7 tablespoon ice-cold water

Filling

1½ pounds sweet potatoes, peeled and sliced into ¼-inch-thick rounds

1 tablespoon plus 2 teaspoons extra-virgin olive oil, divided

½ teaspoon salt

¼ teaspoon freshly ground black paper

1½ cups thinly sliced red onion

1 cup shredded fontina or Cheddar cheese

1 large egg white mixed with 1 teaspoon water

1 teaspoon chopped fresh thyme and/or rosemary

Heat oven to 425 degrees.

For the crust: Pulse the walnuts in a food processor until finely ground.

In a large bowl, mix the ground nuts, flours, chopped herbs, salt and pepper. Make a well in the center and add the oil and water. Gradually stir together to form a soft dough. Knead in the bowl just until the dough comes together. Pat into a disk, wrap in plastic and refrigerate for at least 15 minutes or up to three days.

For the filling: In a large bowl, toss the sweet potatoes with 1 tablespoon of the oil, and salt and pepper. Spread over three-fourths of a large rimmed baking sheet. Toss onion in the bowl with 1 of the remaining teaspoons oil. Spread onion evenly on the remaining fourth of the baking sheet. Roast for 10 minutes. Remove from oven and reduce the temperature to 375 degrees.

Line a work surface with baking parchment, dust with flour and dust the top of the dough with flour. Roll into a rustic 15-inch circle, adding more flour, if necessary, to prevent sticking. Transfer the crust, on the parchment, to a baking sheet.

Leaving a 2-inch border, sprinkle cheese evenly over the crust. At the edge of the border, over the cheese, make an overlapping ring of the larger sweet potato slices. Spread the onion in another ring closer to the center. Using the rest of the sweet potatoes slices, make an overlapping circle in the center of the tart. (Think of a bull's-eye pattern.) Pick up the border of the crust using a spatula and fold over the filling, making pleats in the dough as necessary (it's OK if the dough cracks a little as you fold it). Brush the crust with the egg white mixture. Drizzle the vegetables with the remaining 1 teaspoon oil and sprinkle with thyme and/or rosemary.

Bake until lightly browned on the edges, about 50 minutes. Cool for 10 minutes before slicing.

Serves 12.

“The Simple Art of Eating Well” by Jessie Price and the Eating Well Test Kitchen (2010 Countryman Press)