Here's a Nigella Lawson recipe that I use to turn supermarket tomatoes into gorgeous tomatoes. I love to serve them on some salad leaves with slices of chevre and a few basil leaves. Or delicious on the side of some grilled fish. They take no time to prepare but it's best to make them the day before (or the morning before) you plan to eat them. However I've had great results just from 30 minutes in the oven rather than overnight.
500g (about 24) on-the-vine cherry or other baby tomatoes
2 teaspoons Maldon salt or 1 teaspoon table salt
1/4 teaspoon sugar
1 teaspoon dried thyme
1 x 15ml tablespoons olive oil
Preheat the oven to 220°C/gas mark 7.
Cut the tomatoes in half and sit them cut side up in an ovenproof dish. Sprinkle with the salt, sugar, thyme and olive oil.
Put them in the oven, and immediately turn it off. Leave the tomatoes in the oven overnight or for a day without opening the door.