Sweet Potato, Red Onion & Fontina Tart

Sweet Potato, Red Onion & Fontina Tart

17 Reviews
From: EatingWell Magazine, November/December 2009

Try this roasted-vegetable free-form tart as an appetizer or side dish for a special dinner or as a vegetarian main dish. The pastry dough is very forgiving and quite easy to roll out on parchment paper or a nonstick baking mat. The walnut-studded crust is crisper served warm, but you can enjoy the tart at room temperature or cold too.

Ingredients 12 servings

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Original recipe yields 12 servings
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  • Crust
  • ¾ cup walnuts
  • 1¼ cups whole-wheat pastry flour (see Note)
  • 1¼ cups all-purpose flour, plus more for dusting
  • 2 tablespoons chopped fresh thyme and/or rosemary
  • ¾ teaspoon salt
  • ¾ teaspoon freshly ground pepper
  • ½ cup extra-virgin olive oil
  • 7 tablespoons ice-cold water
  • Filling
  • 1½ pounds sweet potatoes, peeled and sliced into ¼-inch-thick slices
  • 1 tablespoon plus 2 teaspoons extra-virgin olive oil, divided
  • ½ teaspoon salt
  • ¼ teaspoon freshly ground pepper
  • 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


  • Active

  • Ready In

  1. Preheat oven to 425°F.
  2. To prepare crust: Pulse walnuts in a food processor until finely ground. Combine in a large bowl with whole-wheat flour, all-purpose flour, 2 tablespoons thyme and/or rosemary, ¾ teaspoon each salt and pepper. Make a well in the center and add ½ cup oil and water. Gradually stir the wet ingredients into the dry ingredients to form a soft dough (it will seem wetter than other types of pastry dough). Knead in the bowl just until the dough comes together. Pat it into a disk, wrap in plastic and refrigerate for at least 15 minutes or up to 3 days.
  3. To prepare filling: Combine sweet potatoes, 1 tablespoon oil, ½ teaspoon salt and ¼ teaspoon pepper in a large bowl. Spread on three-fourths of a large rimmed baking sheet. Toss onion in the bowl with 1 teaspoon oil. Spread evenly on the remaining one-fourth of the baking sheet. Roast for 10 minutes. Remove from the oven. Reduce temperature to 375 degrees .
  4. Line a work surface with parchment paper or a nonstick baking mat, lightly dust with flour and dust the top of the dough with flour. Roll the dough into a rustic 15-inch circle, adding more flour, if necessary, to prevent sticking. Transfer the crust to a baking sheet with the parchment or baking mat in place.
  5. Leaving a 2-inch border, sprinkle cheese evenly over the crust. Make an overlapping ring of the larger sweet potato slices over the cheese, leaving the 2-inch border. Spread the onion slices in another ring closer to the center. Using the rest of the sweet potato slices, make an overlapping circle in the center of the crust (the pattern will look like a bull's-eye). Pick up the edges of the crust using a spatula and fold over the filling, making pleats in the dough as necessary (it's okay if the dough cracks a little as you fold it); the filling will not be completely covered. Brush the crust with the egg-white wash. Drizzle the vegetables with the remaining 1 teaspoon oil and sprinkle with 1 teaspoon thyme and/or rosemary.
  6. Bake the tart until lightly browned on the edges, about 50 minutes. Cool for 10 minutes before slicing.
  • Make Ahead Tip: Prepare the crust (Step 2), wrap tightly and refrigerate for up to 3 days or freeze for up to 6 months. Cool, cover and refrigerate the baked tart for up to 1 day. Reheat at 350°F for about 20 minutes.
  • Ingredient Note: Whole-wheat pastry flour has less gluten-forming potential than regular whole-wheat flour and helps ensure tender baked goods. Find it in the baking section of the supermarket or online at bobsredmill.com and kingarthurflour.com.

Nutrition information

  • Serving size: 1 slice
  • Per serving: 309 calories; 18 g fat(4 g sat); 3 g fiber; 30 g carbohydrates; 7 g protein; 50 mcg folate; 10 mg cholesterol; 4 g sugars; 7,068 IU vitamin A; 8 mg vitamin C; 76 mg calcium; 1 mg iron; 332 mg sodium; 180 mg potassium
  • Nutrition Bonus: Vitamin A (141% daily value)
  • Carbohydrate Servings: 2
  • Exchanges: 2 starch, 3½ fat

Reviews 17

October 31, 2016
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By: laotters
The crust was too dry.
May 02, 2012
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By: EatingWell User
Tasty. Easy and forgiving, but could be streamlined I took a lot of liberties with this recipe, but it still came out really great. I would make some slight changes next time, but nothing big. The crust: I only had regular whole wheat flour but it came out fine. As per other suggestions I added approx 1 T oil and 2 T water than was called for in the recipe. Next time I would add just a bit more salt (1/4 tsp?) and some garlic. The texture was great, but a bit bland for me. The filling: Used my mandolin to slice the potatoes (1/4 inch, skin on!) and onion (1/8 in) so that part was really easy. I tossed the potatoes in oil, pepper, and salt but skipped that step with the onions - they were still delicious. It was 86 F and HUMID. The AC was off (May just started!) making it about 95 in the kitchen. I the extra roasting step and just rolled out the dough and arranged the veggies/cheese. It took about 60 mins to fully cook at 375F. The veggies were plenty cooked at 50 mins, but the crust looked like it needed a bit longer. I liked the skins on the sweet potato slices - adds fiber and flavor. Pre-roasting the veggies would have turned them into mush and ruined the dish so I was glad I skipped it.
March 12, 2012
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By: EatingWell User
I fell in love with this dish. I am a lover of whole grain, rustic breads, so the appeal for me was a given and I wasn't let down. My 13 year old and I recently became vegetarians and frankly weren't expecting that much flavor from this recipe, we were more interested in the nutrition factor stemming from the sweet potatoes, onions and whole grain. We were so pleasantly suprised by the flavor and texture of this recipe. We used mozzarela cheese, as that's what we had on hand; likewise, we used cashew nuts instead of walnuts and didn't even have thre red onions, just white onions, and still it tasted superb. Making again tonight and had to leave a review this time. You will have to add more liquid to crust, but that's about it.
March 10, 2012
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By: EatingWell User
crust problems! Won't be eating this until later but just wanted to say I agree that this crust is very unforgiving and problematic. I even took the advice of other reviewers and STILL had issues. As much as I love the health benes of the whole wheat flour, I think I may experiment with only white flour next time (King Arthur of course) Pros: haven't eaten it yet! Cons: unforgiving
February 17, 2012
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By: estessa
Super Yummy:) Smells & tastes as good as it looks, did not let us down. I added some white pepper to the crust (in addition to the black pepper), a little more Fontina & drizzled some Oregon White Truffle Oil on top. YUMMY!!!! This Tart will be made again & again in our household:) Cons: The crust could use a little more liquid, but still tasty & workable.
January 03, 2012
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By: EatingWell User
The crust doesn't roll and fold easily. I would try making a slihtly smaller crust and pressing it into a pie tin instead next time
January 01, 2012
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By: EatingWell User
I made this for New Years Eve and it got rave reviews by everyone. I did not have any of the troubles with the crust mentioned in previous reviews. I always scoop my flour--don't know if that helped make sure the crust wasn't too dry. My only problem was that the red onions cooked much faster than the recipe said so some of them burned. I think that might be because my baking sheet was dark. Otherwise, everything was delicious. Pros: Healthy Fats, Beautiful
December 14, 2011
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By: EatingWell User
The dough required about two more TBS of water and 1TBS of oil in order to get it kneadable. Added a little extra rosemary and threw in a TBS of thyme for extra savory flavor. People rave about it when it goes with you to a pitch in. Will definitely make it many more times.
December 10, 2009
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By: Goodfoodie
Besides monitoring the moistness of the dough, I think the dough is too sturdy for a galette shape with large foldovers. The second time I made it more of a conventional tart crust with thin edges and it was much better - not so heavy.
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