1. Pre-heat the oven to 200°C (Gas Mark 6).
2. Cut the tomato vine into a length holding about 4 tomatoes.
3. Blanch the tomatoes in boiling water for about 10 seconds and plunge into ice cold water.
4. Remove the tomato skins and dry well on kitchen paper or a clean cloth.
5. Add the garlic, olive oil, balsamic vinegar and sugar and mix well together.
6. Pour the oil and vinegar mixture into an ovenproof dish and place into the pre-heated oven.
7. When hot, remove the dish from the oven and carefully add the vine tomatoes.
8. Season to taste and baste the vine tomatoes with the hot oil mixture.
9. Return to the oven to roast, basting occasionally.
10. When just cooked, remove the vine tomatoes from the oven and carefully place the roasted vine tomatoes onto warmed plates.
11. Knap the hot juices from the roasting dish over the vine tomatoes and serve immediately.