Take the Lamb leg and make slits and marks with a knife, so it will enable the spices to penetrate deep in the meat and will marinate evenly.
Now for Marination, first rub salt all over the Lamb and deep inside the cuts. Then rub meat supreme, garlic & ginger, green chili paste, raw papaya paste, kachri powder, red chili powder, besan, vegetable oil, yogurt. Keep it aside for 3 hours or preferably overnight.
Take a separate big pot in which the Lamb roast can fit in.
In that pot add 4-5 tbsp of butter/ ghee and put the Lamb leg in the pot and cover it with the lid and let it cook on slow flame from one side after 15 minutes turn it over and allow to cook from another side.
Take it out once it is ready and golden from both sides and meat is absolutely tender and cooked.