A Tart filled with cauliflower and onions sounds not exiting. But if you roast the cauliflower in the the oven and caramelize the onions and if you then add mustard and a flavourful cheese you get a small explosion of diffrent tastes with every bite. There is the sour taste of mustard, sweet from onions, the dark down-to-earth taste of cauliflowers topped with flavour of baked cheese.
I have to admit that it was the mustard that make me curious about this recipe at Smitten Kitchen. Mustard in a Tarte? That sounds good! And it tastes good!