Bring stock, duck, vermouth, tomato paste, orange juice, honey, salt, pepper, cayenne, basil, and dill to a boil. Add sweet potatoes and simmer for 20 minutes. Saute onion and celery in oil and butter for 10 minutes. Sprinkle flour over vegetables, saute for 3 minutes. Add onion mixture to the soup and simmer for 10 minutes. Serve.