Peel and dice the shallots. Cut the carrots into slices. Peel and grate the ginger.
Heat the butter in a saucepan, sauté the shallots, add the carrots, sugar and ginger and glaze. Pour in the vegetable stock and cook the carrots until soft and let cool.
Add the sour cream and finely puree everything with a hand blender and then pass through a sieve. Season to taste with salt, pepper and lime juice and chill in the refrigerator.
To garnish, blanch lime zest and carrot julienne strips and chill in cold water. Serve on chilled plates and garnish with the zest and coriander leaves. The soup can also be served warm.