Peel and wash the carrot and potatoes and cut into evenly sized cubes. Boil up the vegetable stock. Add vegetables, bring to the boil again and simmer for about 15 minutes. Wash the herbs, shake dry.
Cut the chives into small rolls, except for a little to garnish. Pluck parsley and chervil leaves from the stalks and chop. Add the herbs to the broth and puree everything finely with a hand blender. Season to taste with salt and pepper.
Bring the milk to the boil and stir with a whisk until frothy. Serve the soup and carefully add the milk foam and garnish with chives.