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Onion Tart with Mustard and Fennel

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Photo by John Kernick
  • Active Time

    45 min

Simple savory tarts abound in Provence. A particular favorite includes slow-cooked onions, mellow and nearly as sweet as marmalade, punctuated with hints of the herbs that grow wild all over the region—in this case, fennel. Cooks are known to vary their crusts depending on the affair, from short, buttery versions to pizzalike yeast crusts; the latter is used here to keep the tart light.

Ingredients

Makes 8 (hors d'oeuvre) servings

2 1/4 teaspoons active dry yeast (a 1/4-ounce package)
1/2 cup warm water (105-115°F)
1 1/2 to 1 3/4 cups all-purpose flour
1 large egg
1/3 cup plus 1 tablespoon extra-virgin olive oil, divided
2 1/2 teaspoons salt, divided
2 teaspoons fennel seeds
3 pound yellow onions, halved and thinly sliced
1 tablespoon Dijon mustard
1/2 cup grated Parmigiano-Reggiano
  1. Step 1

    Stir together yeast and warm water in a small bowl and let stand until foamy, about 5 minutes. (If mixture doesn't foam, start over with new yeast.)

    Step 2

    Put 1 1/2 cups flour in a medium bowl, then make a well in center of flour and add yeast mixture to well. Stir together egg, 1 tablespoon oil, and 1 1/2 teaspoons salt with a fork. Add egg mixture to yeast mixture and mix with a wooden spoon or your fingertips, gradually incorporating flour, until a soft dough forms. Transfer dough to a floured surface and knead, working in additional flour (up to 1/4 cup) as necessary, until smooth and elastic, about 5 minutes. Transfer dough to an oiled bowl and turn to coat. Cover with plastic wrap and let rise in a draft-free place at warm room temperature until doubled, 1 to 1 1/2 hours.

    Step 3

    While dough rises, heat remaining 1/3 cup oil in a 12-inch heavy skillet over medium-high heat until it shimmers, then sauté fennel seeds until a shade darker, about 30 seconds. Stir in onions, remaining teaspoon salt, and 1/2 teaspoon pepper, then reduce heat to medium-low and cover onions directly with a round of parchment paper. Cook, stirring occasionally, until onions are very tender and golden brown, 1 to 1 1/4 hours.

    Step 4

    Preheat oven to 375°F with rack in middle.

    Step 5

    Knead dough gently on a floured surface with floured hands to deflate. Pat out dough on a large heavy baking sheet (preferably blue steel) into a 15- by 12-inch rectangle, turning up or crimping edge, then brush mustard evenly over dough, leaving a 1/2-inch border around edge. Spread onions evenly over mustard, then sprinkle evenly with cheese.

    Step 6

    Bake tart until crust is golden brown, 30 to 35 minutes. Cut into 2-inch squares or diamonds and serve warm or at room temperature.

Cooks' note:

Onion mixture can be made 2 days ahead and chilled, covered.

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Reviews (34)

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  • I cheated and used a pre-made crust (pâte brisée). It takes a long time (I let the onions cook for over two hours), but it's not at all difficult, and quite good.

    • perrers

    • Grenoble

    • 11/18/2013

  • If you cut this into bite-sized pieces, it's a great hors d'oeuvre for a big party and serves many more than 8. I've made this recipe several times and follow it to the letter, except for cutting back the salt in the crust to 1 teaspoon.

    • Anonymous

    • Newbury, Mass.

    • 12/23/2012

  • This was okay, but probably wouldn't make it again. I added chopped rosemary to the dough, which tasted very good. I wouldn't call this dish a "tart", as the crust is more like a pizza. No problem with any soggy onions. I might try the onions on some other "tart-like" crust.

    • Anonymous

    • Midlothian, VA

    • 12/17/2012

  • This is a wonderful hors d'oeuvre. It really was not alot of work, it just takes some time to prepare. After reading the other reviews, I decided to prepare the onions the night before. I used less oil, as others suggested (slightly less than 1/4c). To decrease the sogginess that others mentioned I covered the onions with a paper towel, rather than parchment paper, while they cooked, drained them into a bowl lined with a paper towel, poured off the excess liquid, and then stored them in a paper towel lined bowl in the refrigerator overnight. I prepared the dough exactedly as given. It was kind of sticky (but it was pretty humid), but using floured hands, it spread pretty easily to the size suggested. The result was a flavorful tart with a nice slightly crispy crust. The minimal leftovers were very good the next day.

    • Anonymous

    • cape cod, ma

    • 7/22/2011

  • Good. I made a test batch of tartlets using the Flaky Cream Cheese Pie Crust from this site. Onions took over two hours, and to help evaporate the liquid, I removed the parchment from the onions after they had softened significantly. Tartlets were okay, but then I topped a couple of them with finely chopped rosemary and a couple drops of good balsamic when they came out of the oven, and that made them much better.

    • llt488

    • Seattle

    • 4/23/2011

  • Really good. Four people polished this off and that was just the appetizer! I had a hard time stretching the dough to fit the dimensions given - and thus thought I had too many onions so I didn't use all of them. Wish I had because they are really tasty! Definately will make again but will either use a different dough recipe or try to stretch as thin as possible.

    • Alpenglow2280

    • NYC

    • 2/23/2011

  • i don't know what i did wrong!! my onions were a soupy mess despite draining at the end and using less oil. i also made a mistake and used puff pastry which made it greasy and not crisp. the onions were also not sweet--and i cooked them on low for 1.25 hours. any suggestions?

    • anitakm

    • 11/25/2010

  • 我做了这个作为复活节的晚餐和开胃菜it was a big winner. Time consuming to make, but I made the caramelized onions the day before to save a little time. One recommendation - drain, drain, drain the onions after cooking or the oil may be a bit much in the final product. Overall, delicious and everyone loved it, would definitely make it again.

    • oh_wow

    • 4/5/2010

  • I used frozen puff pastry crust to make it easier, and it was delicious

    • erininroses

    • Portland, OR

    • 1/21/2010

  • Made this for a holiday party - was easy and tasty! Ingredients are so simple I can make it without planning in advance.

    • Sjayawardena

    • 1/7/2010

  • This is an excellent hor d'oeuvre. So tasty and different.

    • Anonymous

    • Placitaas, NM

    • 11/5/2009

  • Very tasty. It was a little tricky getting the dough to spread out to the dimensions the recipe called for. The tart came out delicious! It was worth the effort. I would use less oil in the onions next time.

    • starltgirl

    • tulsa, oklahoma

    • 10/25/2009

  • This was amazing. I used a premade pie crust to save time and it was still so amazing. It is definitely sweeter than you would expect, but savory also.

    • sizzlesal

    • 8/11/2009

  • Delicious and well worth the effort.

    • Anonymous

    • austin, tx

    • 7/20/2009

  • Delicious, easy to make most stuff ahead. everyone loved this.

    • atongg

    • Delaware River Region, PA

    • 4/25/2009

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