Tomato mustard tart

The ivy on the back wall of the building I can spy from my office has turned a deep, vibrant crimson. We've put away our summer clothes and pulled out our woolen hats, our thick socks, our flannel pyjamas. The toasty smell of the heating rises up against the windows in the morning. But my favorite stand at the green market is still selling plum tomatoes, the last ones of the season, and I am physically incapable of passing them by, no matter how heavily autumn presses upon us. Every week, I buy a sackful of those tomatoes and simmer them into sauces, chop them into Hugo's pastina, turn them into a quick lunch with a piece of cheese and bread. They're still irresistible, despite the winter squash and cabbage that look at me fetchingly from the side.

Tart mise en place

My most recent way to make my way through a pile of tomatoes was to bake a French tomato mustard tart from Clotilde's lovely new cookbook, The French Market Cookbook. A savory olive oil tart dough speckled with poppy and sesame seeds is parbaked, then filled with a savory blend of sautéed onions, mustard and egg. On top go a whole mess of halved, seeded and salted plum tomatoes before the tart goes back in the oven. There, the tomatoes shrink and shrivel, the crust goes crisp, the mustard and onions mellow. We ate slices of the tart hot from the oven and they were very good, but an overnight rest made them truly sing. The next day, Max and I eyed each other ferociously over the last few slices.

(A note: I mistakenly used a tart pan that was too small by a few inches, only realizing my mistake when the tart was already in the oven. Don't follow in my footsteps – make sure you use an 11- or 12-inch tart pan. You want the tart dough to be very, very thin.)

Tart dough

Clotilde is celebrating her blog's tenth anniversary today. Oh, 2003! I still remember first discovering Chocolate & Zucchini just a few months after Clotilde got started and feeling like I'd happened upon something seriously momentous. Her newest book, The French Market Cookbook, is a celebration of the very things that Clotilde has always done so well: simple yet creative vegetarian dishes that are seasonal and delicious, but also very, very beautiful.

One of Clotilde's gifts lies in the ability to take rather prosaic ingredients and transform them into something delectable. This book is full of these ideas. To wit: a stir-fry with barley flakes, carrots and curry; a mashed broccoli casserole on a bed of green lentils and rice; or, the one I'm now most excited to try, poor man's bouillabaisse, with nary a piece of fish in sight (poached eggs and peas take center stage). She updates an old French classic, fontainebleau, with yogurt, but also goes way back with an old-fashioned take on macarons made with walnuts and almonds and sandwiched together with a simple filling of melted chocolate.

Tomato tart

Happily, I have an extra copy of The French Market Cookbook to give away today, in celebration of Clotilde and her lovely site and all the things she made me feel capable of doing all those years ago. So for a chance to win a copy, please leave a comment below and I'll pick a winner at random on Wednesday. Good luck!

Update: Jennifer is the winner and has been emailed. Thank you all for participating – comments are now closed.

Clotilde Dusoulier's Tomato Mustard Tart
Makes 1 11-12 inch tart

tart dough:

1/4 cup (60 ml) olive oil
2 cups (260 grams) all-purpose flour
1 teaspoon fine sea salt
1 tablespoon toasted sesame seeds (optional)
1 tablespoon toasted poppy seeds (optional)
1 large egg

1. Combine the flour, salt and seeds, if using, in a bowl. Add the oil, egg and 1/4 cup/60 ml of water and mix them in with a fork until absorbed. Knead the dough in the bowl until it comes together in a smooth ball.

2. Roll out the dough on a lightly floured surface, turning it every so often, so that it doesn't stick to the surface or pin. Avoid overworking the dough. Transfer the dough to a lightly oiled 11- or 12-inch tart pan and line it neatly. Chill for 30 minutes.

filling:

1 large egg, separated
1 3/4 pounds (800 grams) plum tomatoes
Fine sea salt
2 tablespoons olive oil, more for drizzling (optional)
2 small red onions, thinly sliced
2 tablespoons Dijon mustard
Handful of basil leaves, if available
Freshly ground black pepper

1. Preheat the oven to 325 F (160 ).

2. Brush the tart dough with some of the egg white. Bake for 30 minutes.

3. Halve the tomatoes lengthwise and squeeze out the juice and seeds and core. (Save them for drinking with a sprinkle of salt – so good!) Sprinkle the cut sides with salt and place the tomatoes face down in a colander to drain.

4. Heat the oil in a pan and sauté the onions and 1/2 teaspoon salt over medium heat for about 15 minutes, until the onions are very soft, but haven't taken on any color. Let cool slightly.

5. Stir the egg yolk and any remaining white and the mustard into the onions and spread over the crust. Arrange the halved tomatoes, cut side down, over the onion layer. Drizzle the tart with more olive oil to taste (optional). Bake the tart until the tomatoes are wrinkled and fragrant, 45 minutes.

6. Top with shredded basil and black pepper and serve warm or let cool and store at room temperature overnight before serving.

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224 responses to “Clotilde Dusoulier’s Tomato Mustard Tart – and a Giveaway!”

  1. Molly Avatar

    Yesterday I savored what I think are the last of the season’s tomatoes. Honestly, nothing beats a tomato sandwich. A little shmear of mayo, a few Maldon flakes. Perfection.

    Like

  2. liza Avatar
    liza

    Lovely post, inspires tomorrows dinner. Thanks!

    Like

  3. Honeybee Avatar
    Honeybee

    Yum! Did Hugo have it, too? Or is the mustard to hot for young palate? Our baby mostly wants what we eat now so whenever I come here, I wonder whether a dish you write about is Hugo-approved. 🙂 When our daughter was the same age, I cooked separately for her for a while but that is just too stressful and time-consuming. I need one recipe fits all now!

    Like

  4. suzy Avatar
    suzy

    I’ve enjoyed reading your blog and Clotilde’s for many years!

    Like

  5. Ali Avatar
    Ali

    The tart looks delicious, and I, too, cannot wait to try the poor man’s bouillabaisse.

    Like

  6. Constance Avatar
    Constance

    I don’t love tomatoes, but this is beautiful enough to try for guests!

    Like

  7. Abby Avatar
    Abby

    That tart looks amazing and I would love to win The French Market Cookbook to get some kitchen inspiration!

    Like

  8. Sasha Avatar

    I love the idea of adding mustard to a savoury tart. It is such an obvious idea that I can’t believe I never thought of it! I also love the sound of those macarons. In other words, I have my thumbs pressed for this giveaway. It sounds like a brilliant cookbook, and one that is very au courant.

    Like

  9. donaji Avatar
    donaji

    This tart looks amazing! And luckily I have tomatoes in the kitchen, this is going to be lunch this week!!

    Like

  10. Mallory @ Because I Like Chocolate Avatar

    I love all the seeds in the crust. So simple yet so beautiful. And I’m sure it tastes amazing.

    Like

  11. EM Avatar
    EM

    This would be a great recipe to try with the heaps of dijon mustard sitting in my cupboards and fridge (from a mustard chicken with onions recipe that I am taking a break from… made it many times.) My husband (much more of an experiemental and adventurous cook than I am) would probably fall over in shock if I did something else with the dijon mustard!

    Like

  12. Allison Avatar
    Allison

    I need to make that tart tonight! It looks so good.

    Like

  13. Adrienne Avatar

    And here I thought I was done with tomatoes this year… Will have to cross fingers and hope there are still some good ones at the market in a couple of days, this looks like quite a treat.

    Like

  14. Heidi Avatar
    Heidi

    I love tomato tarts! This one looks delicious. Can’t wait to try it.

    Like

  15. Katrin Avatar
    Katrin

    Thank you – an oil based tart dough is perfect for so many things (in our saturated-fat-poor diet for my husband!) and since we still have some tomatoes at the market – this will be fabulous!

    Like

  16. apukhraj Avatar
    apukhraj

    How lovely! My favorite tomato tart recipe comes right at the end of summer. I better rush to it.

    Like

  17. Caitlin Avatar

    This looks so good! And the book sounds like pure heaven for me. Brava Clothilde!

    Like

  18. Leila Avatar
    Leila

    Looks delicious! I love love love your blog and your book. I was a grad student at Tufts last year and my memory of your book talk that rainy night in Harvard Square is one of my favorite’s from my time in Boston. Will be sure to check out Clotilde’s blog too.

    Like

  19. Jessica Avatar
    Jessica

    mmm… this looks fantastic. This may have to be dinner tomorrow.

    Like

  20. Kathryn Avatar
    Kathryn

    I’m so into French cooking these days. I want to try everything. It all started with a small bottle of Pimente d’Esplette a friend brought back from Sarlat. I hope I win!

    Like

  21. AEH Avatar
    AEH

    I’ve always loved Clotilde’s blog and am eager to try my hand at the lovely tart!

    Like

  22. Bronte Avatar
    Bronte

    Looks lovely, as does everything you post here! I need to start my own blog chronicling my way through all the recipes I’ve bookmarked from yours.

    Like

  23. Elizabeth Avatar
    Elizabeth

    This looks so delicious! Thanks for a chance at a copy of Clotilde’s book!

    Like

  24. Lizounette Avatar

    I loved her first cookbook. That tart looks amazing!

    Like

  25. nans Avatar
    nans

    This recipe really makes me regret that my tomato crop this year was beyond pitiful. Bookmarking it for next year!

    Like

  26. Louisa S. Avatar
    Louisa S.

    This recipe looks fantastic and the book sounds perfectly inspiring!

    Like

  27. Sarah G. Avatar
    Sarah G.

    Beautiful photos of this dish! And I love that you’ll be choosing a winner on WEDNESDAY 🙂

    Like

  28. PamB Avatar
    PamB

    lovely tart – and good timing – farmers market trip yesterday yielded tomatoes, when I already had oodles of tomatoes on the counter already that need some attention

    Like

  29. Sydney Avatar
    Sydney

    This looks amazing delicious and I’ve been looking for a good vegetarian cookbook that relies on fresh ingredients for quite a while now, this book sounds perfect!

    Like

  30. Rachel Avatar
    Rachel

    I was just thinking I needed to make a tomato tart about now! Thanks for a lovely giveaway! 🙂

    Like

  31. dervla Avatar

    aww congrats to Clotilde, and to you, your posts always make my day a little brighter.

    Like

  32. Magdalen Avatar
    Magdalen

    Looks great! Thanks for the giveaway 😀

    Like

  33. Patricia Avatar
    Patricia

    Wednesday is my third anniversary with mr wonderful 🙂
    thanks for the great blog.

    Like

  34. Lena Avatar

    I haven’t made a tart in ages, or so if feels, and this tomato mustard tart sounds lovely. I’ll have to check tomorrow if I can still find local tomatoes at the market, but if I do, I’ll have to make this as soon as possible. Maybe even tomorrow evening.

    Like

  35. fridica Avatar

    I have JUST discovered her blog a few days ago and I dare say I felt the same thrill as you did 10 years ago! Would love to win this!

    Like

  36. Amy Avatar
    Amy

    I am also clinging on to summer by scooping up the last of the flavorful tomatoes. Thanks for the tart inspiration!

    Like

  37. RA Avatar

    Ooh, that tart looks lovely! Thanks for the giveaway opportunity!

    Like

  38. Annie Avatar

    not so long ago I won a copy of My Berlin Kitchen and was delighted. Would love to win a copy of Clotilde’s book!

    Like

  39. Jennifer Jo Avatar

    I’d love to add that cookbook to my already sagging shelf!

    Like

  40. Sarah Avatar
    Sarah

    Oh I am going to make this for my mother and I for lunch today! I bought some beautiful heirloom tomatoes at the farmers market on sunday and have been wondering what to do with them. I too remember being thrilled to find Clotilde’s blog many years ago too. Her book looks beautiful.

    Like

  41. Robyn Avatar
    Robyn

    Tomatoes, onions and mustard cooked together in a tart sounds divine 🙂

    Like

  42. Giulia Pines Kersthold Avatar

    Wish I had seen this before I decided to have leftover chicken noodle soup for dinner (although it was Smitten Kitchen’s chicken noodle soup, so I still win)!
    I’ve had tomatoes from Brandenburg burning a hole in my fridge for days now, and I just realized with that little jolt of satisfaction that I have all the other ingredients for this recipe as well.
    Don’t get too squishy before tomorrow little guys, you’re turning into a pie!

    Like

  43. Liz Avatar
    Liz

    I am also rushing to make tomato heavy dishes before fall really sets in. Squash can wait 🙂

    Like

  44. tracy crandall Avatar
    tracy crandall

    I am sooooo going to make this….looks amazing!

    Like

  45. katie Avatar
    katie

    I used Clotilde’s guide to Paris restaurants and food shops when I visited the city a few years ago. Her advice was spot on.

    Like

  46. tessa Avatar
    tessa

    mhmmm, that looks good!

    Like

  47. Natalie Matuszczak Avatar
    Natalie Matuszczak

    What a great way to celebrate the transition from summer to fall! I have to try this. I’ve enjoyed tomatoes all summer by using them to make your sauce from My Berlin Kitchen (with carrots and onions)! It’s become a favorite.

    Like

  48. Karina Avatar

    Tomatoes on bread is one of my favorites. (or, uh, ketchup. with cheese. Midnight, dontcha know) My mom grew tomatoes this year, and while there aren’t any left-turned the rest of the unripe ones into green tomato sauce, for which I feel a disproportionate amount of pride-maybe we can grab some at the market for a tomato tart.

    Like

  49. dorota Avatar
    dorota

    this looks delicious.

    Like

  50. Miriam Avatar
    Miriam

    Looks delicious! I’ve been meaning to pick up a tart pan, and this is just the recipe to make me do it!

    Like