1. Preheat oven to 220°C, gas mark 7.

2. Brush 15ml of olive oil over the base of a roasting tin.

3. Put in the tomatoes, cut-side up, then tuck in the onion wedges, garlic and thyme.

4. Scatter over the lemongrass and sprinkle with the sugar. Season with pepper, then drizzle the rest of the oil all over.

5. Roast for 50 minutes, stirring after about 30 minutes, until the tomatoes and onions are very tender and catching at the edges.

6. Place in a blender, making sure to scrape down the caramelised residue stuck to the bottom of the pan.

7. Pour boiling water over the Major Mediterranean Vegetable Stock Base Paste and Major Light Vegetable Stock Base Paste and mix well.

8. Add to blender and liquidise well.

9. Rub the soup through a sieve to remove all the tough bits of lemongrass, garlic skin and thyme.

10. Serve lightly chillied or reheat.

11. Garnish with chives.