Dissolve ground saffron in 4 tablespoons of boiling water and set aside (click for How to Use Saffron).
Heat the butter and oil over medium heat in a large pot. Add half of the sliced onions and saute for 5-6 minutes. Add the turmeric powder and stir. Put the lamb shanks on the onions.
Fry the lamb shanks until nicely browned on all sides, about 4 minutes. Then top with the garlic, celery, carrot, bay leaves and remaining onions. Add the ground cinnamon.
Cover the pot and reduce to low (do not add water). Cook over low heat for 1 hour and 45 minutes (do not stir, just shake the pot occasionally).
Add the dissolved saffron, salt and pepper. Cover the pot and cook for 2 hours or until the meat falls off the bone easily (long cooking is required so the meat falls from the bone). Turn the lamb shanks every 30 minutes so they cook evenly. Add more boiling water if needed.
At the end, discard the bay leaves. Your lamb shanks are ready to serve!