Wash and scrape the carrots. Cut 1 - 2 carrots into julienne strips and set aside.
Finely dice the remaining carrots, simmer with bay leaf and grated lemon zest in vegetable stock for approx. 15 minutes. Remove the bay leaf, strain the soup through a sieve or puree it, season with lemon juice, salt and pepper.
When serving, add a dollop of sour cream to the soup and garnish with the julienne strips and lemon balm or mint leaves.