Recipe

Mustard Greens Tart with Caramelized Onions and Gruyere

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Photo by EmilyC

This recipe was entered in the contest for Your Best Late Winter Tart (Sweet or Savory)

This recipe was entered in the contest for Your Best Greens
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EmilyC's Notes: If I had to choose a favorite green, it would be mustard greens, which often takes a backseat to the more common swiss chard, kale, and collards. I combined the best elements of several recipes...
If I had to choose a favorite green, it would be mustard greens, which often takes a backseat to the more common swiss chard, kale, and collards. I combined the best elements of several recipes from two of my favorite cookbooks, Sunday Suppers at Lucques and Zuni Cafe, to create a tart that would highlight the bright, peppery notes of this unsung ingredient.

This tart is all about building layers of flavor. It starts with a base of ricotta and greek yogurt; a layer of gruyere cheese; and then a mixture of caramelized onions and sautéed, garlicky mustard greens. This same filling could work in a tart shell or even a galette, but in my mind the flaky, buttery puff pastry makes the perfect canvas.

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Serves 4

1 sheet (about 8 oz) frozen all-butter puff pastry, slightly thawed Ask a question about this ingredient

2 egg yolks Ask a question about this ingredient

4 tablespoons plus 1 teaspoon olive oil Ask a question about this ingredient

3/4 pounds yellow onion, thinly sliced (about 3 cups) Ask a question about this ingredient

2 teaspoons thyme, finely chopped Ask a question about this ingredient

1 bunch mustard greens, stems and center ribs discarded, leaves cut into wide ribbons Ask a question about this ingredient

2 large garlic cloves, minced Ask a question about this ingredient

1/4 cup whole milk ricotta Ask a question about this ingredient

2 tablespoons whole milk greek yogurt Ask a question about this ingredient

1/2 cup gruyere cheese, shredded Ask a question about this ingredient

kosher salt and pepper, to taste Ask a question about this ingredient

1/2 lemon, for juicing Ask a question about this ingredient

Heat a large sauté pan over medium-high heat for 1 to 2 minutes. Add 2 T olive oil, then the onions and thyme. Stir to coat the onions in the oil. Once the onions have started to color, lower the heat, stir in a few pinches of salt and pepper, and cook until the onions are a golden, amber color -- about 25 to 30 minutes. Take your time with this step; the flavor is worth it.
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Meanwhile, heat a large sauté pan or dutch oven over medium heat for 1 to 2 minutes. Add 2 T olive oil, then the garlic and cook, stirring frequently, about 30 seconds. Add the greens and toss with tongs to coat uniformly with oil. When they begin to wilt, add a few tablespoons of water, cover, and cook for about 5 minutes, stirring occasionally. Uncover and continue to cook until greens are tender and water has evaporated, another 1 to 2 minutes. Season with salt (no pepper is needed because they're naturally peppery!). Remove from pan; wrap the mustard greens in a dish towel (or paper towels) and squeeze to remove excess moisture. Don't skip this step because it will prevent a soggy crust.
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Mix together the caramelized onions and mustard greens; set aside.
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Preheat the oven to 400 degrees F.
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Combine ricotta, egg yolk, yogurt and 1 teaspoon of olive oil in the bowl of a food processor. Puree until smooth, then season with salt and pepper; set aside.
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Place the slightly thawed puff-pastry sheet on a parchment-lined baking sheet. Make an egg wash by combining 1 egg yolk with enough water to loosen. Score a 1/4-inch border around the edge of the pastry, then brush the border with the egg wash.
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To assemble the tart: Spread the ricotta mixture evenly on the puff pastry within the border. Sprinkle the gruyere over the ricotta. Arrange the caramelized onion - mustard greens mixture on top.
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Bake the tart for about 25 minutes. The crust should turn golden brown and the cheese should bubble. Lift up the crust to make sure it's crisp and fully cooked before removing from the oven. (I find it helpful to use a spatula to peek under the tart -- the crust should be pretty crisp and stiff, with slight give in the middle, when it's done.)
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Squeeze lemon juice over the tart and serve.
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11 Comments on Mustard Greens Tart with Caramelized Onions and Gruyere

gingerroot added 8 months ago

This sounds amazing. My CSA keeps me supplied with a steady course of mustard greens and I can't wait to try this.

EmilyC added 8 months ago

Thanks so much, gingerroot! Let me know if you try it!

AntoniaJames added 8 months ago

This looks so tasty! I've not used mustard greens much. That's going to change this week, when I try this. Yummmmm. ;o)

EmilyC added 8 months ago

Thanks AJ! I'd be thrilled if you try it! The first time I made it, I used puff pastry from Trader Joe's. For a real treat, I've also used Dufour puff pastry, which is a bit pricey but puffs up sky high and tastes wonderful. A sheet of it is 14 oz, so I doubled the ingredients and that worked well. Enjoy!