Caramelized onion and tomato tart with balsamic reduction


I first attempted, and succeeded at, making crust that was destined for the best ever tomato tart around this time last year. It was our first summer in the new house, and even though aren’t exactly whizzes in the garden department, we managed to have lots of ripe tomatoes all at the same time. I’d been making them into gaspacho all summer long, and felt the need to try something different. I whipped up a savory tart crust, garnished with caramelized onions, zucchini and plenty of juicy tomatoes, a bit of crème fraîche and some fresh herbs, and my tomato tart was born. Although I’ve only made it a couple of times since, the recipe has stuck with me. I even considered it for my food truck, calculating the cost of making one tart and the price of each slice divided by all of my overhead… So yes, this recipe has a special place in my repertoire, and since summer is in full swing, I decided to share it here today.


There’s something about a tart that is so satisfying. It takes more work than a sandwich, but the butter crust and roasted vegetables so make up for that. The crust is super simple to throw together and doesn’t need to be par-baked. Just let it rest in the fridge for a couple of hours, roll it out, top it to your liking and bake for a good 35-40 minutes, and you’ll have a tart! You can certainly do whatever you want to your own tart, but I highly recommend the mixture of caramelized onions, tomatoes and balsamic reduction. Add a few dried herbs, a pinch of sea salt, a dollop of crème fraîche and this tart transcends from good to heavenly. Top it off with a bit of grated cheese and it’s just plain perfect.


Caramelized onion and tomato tart with balsamic reduction

2 C flour
1 1/2 t salt
1 1/2 sticks of butter, cold and cut into cubes
6-7 T ice water

Plenty of ripe tomatoes: I used a mix of heirloom, roma and green
2 T olive oil
2 large onions
1 t sugar
2 T butter
1/4 C crème fraîche or heavy cream
Herbes de provence or other dried herbs
Sea salt and pepper
Shredded cheese (optional)
1/2 C Balsamic vinegar (optional)


For your crust: whisk together the flour and salt. Blend in the butter with your fingertips or a pastry blender until it looks like coarse meal. Add the ice water, 1 T at a time, tossing with a fork to incorporate. Stop once dough begins to form and come together in your hands. On a floured surface, knead the dough 3-4 times, form into a ball and refrigerate for one hour covered in plastic wrap.


Begin prepping your veggies. Cut the tomatoes into thick slices and toss them in a bowl with the olive oil, herbs, salt and pepper. Heat some butter in a skillet for the onions. Cut them into thin slices and cook slowly over low heat for about 30 minutes, until they’re translucent and slightly caramelized. Adding a pinch of white sugar will help them develop a deeper flavor, I recommend it! Once cooked, mix in the crème fraiche and line your pie crust with this mixture.

In another saucepan, heat 1/2 C balsamic vinegar over medium heat. Let the mixture cook down until it has reduced by about 2/3. It should be thick and syrupy and that awful vinegar smell should be just about gone when you smell it. Set aside until the tart is assembled.


Now you’re ready! Spread your marinated tomatoes on top of your onion mixture, drizzle with balsamic reduction and a bit of cheese, if you like. Heat your oven to 375° and bake tart for about 45 minutes, until cheese is bubbly and crust is done throughout.



4 thoughts on “Caramelized onion and tomato tart with balsamic reduction

  1. Ooooohhhh. That balsamic reduction looks so rich and syrupy. From the looks of it, I don’t see how this tart could be anything less than fabulous. Did you use red onions, vidalia, or white?

    • I used vidalia. I’m guessing any of those would be great though. And I love balsamic reduction. It couldn’t be easier to make and adds so much flavor!

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