Heat oven to 200C/180C fan/gas 6. Peel the carrots and slice on the diagonal to the thickness of a £1 coin.
Heat the oil in a 23cm ovenproof frying pan and cook the onion gently until softened and lightly golden. Transfer to a bowl, toss with the semi-dried tomatoes and set aside.
Heat the butter and sugar in the frying pan, add the carrots and 100ml water and cook very gently for 15 mins until the water has reduced and the carrots are golden and tender.
Arrange the carrots in a single layer on the bottom of the frying pan. Spoon the onion and tomatoes on top and cover with a layer of cheese.
Roll out the pastry about 1.5cm bigger than the pan, and trim. Lay the pastry over the top of the pan, tucking in around the carrots as you go. Bake in the oven for 30 mins until the pastry is golden
and cooked through.
Remove from the oven and leave to stand for a few mins. Invert the tart onto a serving plate and lift off the pan using a spatula. Serve warm with a crunchy seasonal salad.