Heat all ingredients except leeks to boiling in Dutch oven. Reduce heat. Cover and simmer 30 minutes. Add leeks. Heat to boiling; reduce heat. Cover and simmer until thickest pieces of chicken are done, about 15 minutes. Remove chicken from broth and cool slightly. Remove chicken from bones and skin; cut chicken into 3 cm pieces. Skim fat from both. Remove bay leaf.
Add chicken to broth. Heat until hot, about 5 minutes.