- Very finely chop the leek; chop parsnip and carrots also; set them aside. preheat oven at a temperature of 400*F.
- In a roasting tin, place carrots and parsnips and according to your taste buds, season with salt and pepper. Roast for one hour or until the vegetables are very soft.
- Meanwhile, just before 20 minutes when vegetables have finished roasting, add leeks along with the soup and 1 tsp of thyme in a large saucepan. Let simmer and cover for 20 minutes.
- In a blender, put roasted root vegetables and blend, if necessary add little soup. Transfer it into a saucepan and check the taste. If desired, add more seasoning. Stir and simmer for five minutes.
- Transfer into serving bowls and garnish with thyme sprigs.