Add the chicken broth, lentils, sausage, carrots, celery, onion, potatoes, thyme, and bay leaf to a large pot.
Bring the soup to a boil, then reduce heat and simmer for 30-40 minutes, until the lentils and potatoes are tender.
Discard the thyme sprigs and bay leaf.
Ladle the soup into bowls and top with chopped parsley.
