Rustic Onion Tart

I recently observed my friend Suzanne whip up a couple onion tarts for a family meal and was so impressed by the wonderful flavor of the caramelized onion, I decided to try my hand at it. I’ve deviated a bit from Suzanne’s recipe, and have followed some tips from Helen of Beyond Salmon who has a lovely tomato onion tart posted on her site to come up with the following recipe. We all loved it. Making an onion tart may a little involved, but if you are using a packaged frozen crust (use the flat or folded kind), it’s very easy. Caramelizing the onions takes an hour, but you don’t have to stir them that often. However, if you are making a crust from scratch, as I am prone to do, well, that’s a whole other level of complexity and of course, rewards.

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Rustic Onion Tart Recipe

  • Yield: Serves 4.

Ingredients

  • 1 Pâte Brisée (tart dough) for one 10-inch tart (see method for making pâte brisée) or 1 packaged, flat pie crust (Trader Joe's has one in their frozen section)
  • 3 medium sized red onions
  • 2 Tbsp olive oil
  • 1 Tbsp butter
  • Salt
  • 1 teaspoon balsamic vinegar
  • 3/4 cup (not packed) roughly grated Gruyère Swiss cheese

Method

1 If you are making a crust from scratch, prepare the dough and let it chill in the refrigerator while you are cooking the onions.

2 Peel and slice the onions, lengthwise from stem to root. (See How to Slice an Onion)

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3 Heat olive oil and butter in a large, heavy-bottomed sauté pan on medium heat. Once the butter has melted, add the onions and sprinkle a little salt over them. Cook, stirring occasionally for 10 minutes, until the onions have softened and are translucent. Reduce the heat to medium low and cook for an additional 40 minutes, stirring occasionally, until the onions are well browned. Add balsamic vinegar and cook for 10 minutes more, until onions are completely caramelized. Remove from heat.

4 Preheat the oven to 450°F. Remove the dough from the refrigerator and let stand for 5 minutes before rolling it out. Roll out the dough on a lightly floured surface to a 10-inch diameter. Remove the crust dough to a cookie sheet lined with parchment paper.

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5 Place all but a couple tablespoons of the cheese in the center of the dough. Spread to within 1 1/2 inches from the edges. Add the caramelized onions, layering them on top of the cheese. Fold the edges of the crust dough over so that a small circle of onion is still showing in the centre of the tart. Sprinkle the remaining cheese over the top of the tart.

6 Place in the oven on the middle rack. Bake for 10 minutes at 450°F. Reduce the heat to 350°F and bake for an additional 20-25 minutes, until the crust is golden brown. Remove from oven and let sit for 10 minutes before serving.

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24 Comments

  1. Alanna

    Gorgeous … with the addition of maybe a tablespoon or two of brown sugar, this is how I cook (and cook and cook and cook) onions for fajitas. I’m curious: have you tried the Trader Joe’s pie crust?

  2. Kate

    Wow, this looks delicious. Carmelized onions sell me on any recipe. Alanna, I like Trader Joe’s pie crust… actually I like almost anything from Trader Joe’s! Although, homemade pie crust can’t be beaten.

  3. Ari

    Just a comment about the TJs Pie Crust – I haven’t used it personally, but I know from experience that it’s seasonal – you can probably find it now through Feb or so, but they don’t have it year round.

  4. Lady Amalthea

    Oh, onions always make me happy, especially caramelized. I must try this.
    BTW, TJ’s crust is the best pre-made one I’ve found.

  5. art-sweet

    An awful lot of the premade pie crusts still use lard (buh-bye vegetarian recipe, hello stomach cramps all night long). Anyone know of a good one that doesn’t? Does the TJ’s crust have lard in it?

  6. Mark

    I’m always looking for any new and different recipies with onions and boy was this different. Enough to be a favorite when people come over. Love it!

  7. Marianne

    Elise, I made this tonight and it was really wonderful! I’m writing it up as we speak–thanks for the recipe.

  8. Laura

    This is a rich, delicious tart. I made the onions the day before, assembled and baked the tart the next morning and reheated it just before serving. Obviously this is a forgiving recipe and a much appreciated one as well. Thank you!

  9. Liz

    This was absolutely fantastic, and so easy! You really can’t go wrong with caramelized onions and gruyere– so delicious! I think this will be a go-to dish when I need a quick savory appetizer.

  10. cheryl

    Anyone know of a good gf crust that can be used for the tart?

    Thanks!

    Cheryl

  11. Erin

    This was truly divine! Cheated and used a store bought dough, but a using cave-aged gruyere more than made up for it. Thanks for a fabulous recipe that I’ll be sure to make again and again.

  12. Sarah

    Could I put this together for a party and let it sit in the fridge for an hour or so before baking?
    Also, if I wanted to add a little meat to this would you reccomend a sweet italian sauasage or prosciutto?
    Thanks, it looks like an easy summer beauty.

    I don’t think there would be a problem with letting this sit in the fridge for an hour before baking. Regarding meat, both Italian sausage and prosciutto sound like delicious additions. ~Elise

  13. margaret

    I have doubled this and saved one in the freezer, swathed in its parchment paper and then snugged in foil. I took it out and let it come to room temp then popped it in the oven. It was just as good as the freshly made. You can also roast the onion in the oven if you can’t tend the stove.

  14. Marisa

    This is so easy and forgiving. I’ve made this several times but one day dinner plans changed. I assembled and placed in the fridge for 2 days! Baked it and it tasted just as good as all the other times. Now I make it 1 day in advanced for dinner parties, delish.

  15. Not that Carrie, the other Carrie

    This sounds absolutely amazing, but has anyone ever tried it with other than red onions?

    I have such a problem with them, I think they smell like b.o. *shakes head* don’t ask, I have no clue.

    What about a big mound of Vidalia or just yellow and whites?

    You can easily make this with other types of onions. Go for it! ~Elise

  16. Grace

    This has become a favourite in my family after only one appearance (for my mom’s 60th birthday)–and now its going to make an encore performance for Thanksgiving. I just carmelized my onions and will soon set to making my mom’s recipe for a “water-whip” pie crust that we all dearly love. I’m planning to freeze it tonight (as per margaret’s direction above) and then thaw it tomorrow morning and toss it into the oven in time for it to come out just before the turkey and act as our appetizer. Thanks for the new family favourite! I’m passing this one on to my kids (that I don’t have yet). :)

  17. JT

    Delish. Just finished and tested. Beautiful to boot. Easy. Been hankering to make this for some time. Today was the day. Definitely making for friends as a prelude to chicken marsala. Used Gruyère (missed the Swiss cheese part)…but was very tasty. Trader Joe’s crust. (I put the tart on a few paper towels while cooling to drain some of the butter from the crust.) Only thing I would recommend would be to try the carmelized onions before putting in the crust and adjust to taste. Thanks, Elise…I love looking like a pro!!

  18. Joan

    Since I made this only for myself as a test yesterday – I have lots of leftovers. I just popped a piece of the tart in the microwave today and all I can say is: Did I really make that? :) I don’t know what it is – but the day I’m cooking, I truly have a hard time knowing the full impact of a dish’s flavors. Probably comes from working with the food too much. I only wish I could eat the entire thing…right now; that good. My only concern yesterday was seeing how very rich the pastry was…But – as a treat – what the heck. My friends are going to love your recipe. You KNOW I do.

  19. Gayle

    I made three of these tarts for Christmas dinner with the family. I used a mix of sweet onion and red onion, and a purchased whole wheat crust for one tart and regular crusts for the other two. If I heard it once I heard it 20 times: “This is the best thing we’ve had tonight! You have to make this for every family gathering from now on!” They were fighting over who could take some home – someone hid most of a tart for himself. Anyway, it’s a great recipe: simple and flexible. Use other cheeses than gruyere if you like (I did). I may add a small layer of other vegetables and/or seasoned ground meat to make it more of a meal…

  20. JBJ

    This was GREAT! Words cannot express. I changed it up a little and used Pilsbury cresent rolls as my crust and it worked just as well and quicker. Now a favorite!

  21. Wunderkind

    A friend recommended I try this recipe, and I love it! I’m not a big fan of Gruyère cheese, or balsamic vinegar, so I left both out and just added some sugar to the onions. My mom loved it so much she had me bake a ton of mini tarts for her birthday party.

    I’ve found that onions also taste quite good on pizza bases with a bit of a pizza tomato sauce and roasted baby tomatoes. To counterbalance the sweetness I added some blue Danish cheese just before the whole thing went into the oven.

  22. Lianne

    Can the onions be carmelized the day before and refridgerated, then put in the crust & baked the next day?

    Yes. ~Elise

  23. tt

    Can a store bought puff pastry replace the pie crust?

    If I were to use puff pastry, I wouldn’t fold it over the center like you do with a regular pie crust round. I would pile the filling on top of the puff pastry, just up to an inch from the edge. ~Elise

  24. Mari Anne Souza

    We have a winner! Made 2 of these for Christmas Eve, to go along with other appetizers. Everybody loved them. I used the pre-made pillsbury dough. I’m going to try it with puff pastry. Thank you, very much!

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