Remove duck meat from skin and bone, wash and cut into pieces. Peel and chop the onion. Heat oil in a pot. Brown meat and onion in it. Season with salt and pepper. Pour broth over it, bring to the boil and cook for 30-40 minutes.
Clean the fennel, put some green aside. Wash the fennel and cut into strips. Add the beans, fennel and tomato sauce about 15 minutes before the end of the cooking time. Season to taste with thyme. Arrange on plates and garnish with fennel green