1. Soak legs in water for few hours, changing water once or twice. 2. Remove from water and make random incisions along legs. 3. In a dish mix all ingredients for marinade. Massage into legs and leave covered to marinate overnight in fridge.4. In a deep pot, add ghee (Clarified butter), heat, then place down carrots, onion and tomato slices. This will add flavor to lamb, aswell as be part of gravy and most importantly prevent the lamb from catching to bottom of pot.5. Place lamb over veggies, with all the marinade.6. Pour in Coca-Cola and add 1 ½ cups water. The Coca-Cola, mustard powder and brown vinegar will aid in tenderizing the meat.7. Cook on med-low heat until meat is tender. You will have to turn legs over twice in between to cook thoroughly and evenly. Test to see if it is cooked through by poking with a knife. It will push through easily when done.8. Remove legs and place in casserole dish. Becareful with it being hot.9. Spoon some marinade onto the cooked legs, coating all over. Spoon remainder marinade and veggies into a blender with ¼ cup water. Blend until smooth.10. Pour blended mixture in a saucepan, add butter and bring to boil. This will become pouring gravy. Pour into gravy boat.11. Place legs under hot oven grill and redden for few minutes.12. Serve with roti/garlic loaf, roasted veggies/garlic potatoes and gravy.