Place the beef shanks in the slow cooker. Heat the broth and once hot stir in the saffron until it is mixed. Put broth over beef shanks in the slow cooker.
Top the beef shanks with cumin and lemon slices. Put some pats of the ghee on top of each shank.
Cook on low in the slow cooker for 8-9 hours. Serve with bread or cous cous.