slow roasted tomato tart with caramelised onions and gruyere

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tomatoes about to be slowly roasted

This recipe evolved over the day as I was cooking all the other things for my birthday.  When I have a lot of tomatoes that need to be used up, I roast them either with a few herbs or with garlic and onions and then normally whizz into a delicious tomato sauce (for pasta, chicken, fish etc). Slow roasting them is another solution. I cut about 10 tomatoes in half, drizzled with olive oil and sprinkled generously with thyme and maldon salt and roasted at 150 degrees for about an hour and a half.  The flavour of the tomato intensifies so dramatically it really is worth the time and effort on this one.

roasted and ready

I doubled the recipe below as I made a 30cm tart. 

recipe:

  • pastry:
  • 200gm flour
  • 100gm butter
  • 50gm parmesan cheese, finely grated
  • 1 egg
  • filling:
  • 1 red onion thinly sliced
  • 1 Tbs balsamic vinegar
  • 1 Tbs brown sugar
  • a knob of butter
  • 50 gms of guyere cheese grated
  • 5 tomatoes
  • olive oil
  • thyme

how to make:

  • Cook the tomatoes as per above
  • To make the pastry, whizz the flour and butter in a food processor until it resembles breadcrumbs. Stir in the parmesan, then the egg, and bring together to make a dough. Wrap in cling film and chill for 20 minutes
  • roll the pastry out to cover a 23cm low tart tin (I doubled the pastry to make a bigger tart and found that I had too much) and bake blind for 10 minutes. Remove from the oven and take out the baking paper and beans etc and bake for a further 5 minutes. Allow to cool a bit
  • melt a knob of butter in a frying pan and gently fry the onion until soft.  Add the balsamic vinegar and sugar and cook for a few more minutes until the onions are nice and gooey (do either one or two onions)
  • spread the caramelised onion over the bottom of the tart, sprinkle over 80% of the cheese, then layer the slow roasted tomatoes on top, cut side up and sprinkle over the remaining 20% of the cheese.
  • bake for about 20 minutes @ 180 degrees

This was a complete success and not only does it look beautiful, the intense tomato-ie-ness, the sweet onions and the nutty gruyere marry so well together.

succulent and crunchy tart

The pastry is  really easy to make an has a nice crisp texture (reminiscent of a cheese straw)– so I will definitely use this again.  I had a bit extra as I doubled the recipe, so made another small tart and filled this with some odds and ends from my fridge, onion marmalade, courgette slices, feta, olives and gruyere.

an extra tart with bits and pieces lying around

3 Comments

  1. I have just made your slow roasted tomato tart and it was superb!! Thank you very much for sharing the recipe. It will be made again for sure!

  2. Turned out great! Used an 8.5 inch tart pan, 1 yellow onion and 1 red onion, and doubled the gruyere. I live in the US so weighing everything was a bit different because we use cups for dry ingredients. If you also live in the US, make sure you roast your tomatoes at 300 degrees fahrenheit and bake the tart at 350 degrees fahrenheit. Roasting the tomatoes before baking was a complete game changer. Great recipe!

  3. Thanks for the comment Jenna and your tips for the recipe.

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