Chicken broth bring to boil, add bay leaf and chicken fillet. Cover and cook on low heat for 20 minutes.
Take out fillet from the broth, add carrots, celery and simmer covered for 10 minutes. Then add leeks and simmer 5 minutes. Add lemon zest, pour lemon juice and remove from heat.
Chicken fillet cut in pieces and add to soup. Salt, pepper and sugar to taste.
Pour cooked soup in bowls and garnish with greens and lemon slices.
Ready in: 45 minutes.