To make your own Nihari masala, dry roast all the whole spices for the masala; cool; and grind them to a fine powder.
Heat Ghee (you can use oil as well but ghee makes it tastier) in a deep bottom stock pot. Once the ghee is hot, add the sliced onions and fry till they start to turn brown.
Add mutton pieces, ginger paste, garlic paste, coriander powder, turmeric powder and salt.
Mix well to coat the mutton in ghee and spices. Sauté for 5 mins.
Add the nihari masala and 8 cups of water. Mix well, cover and cook on very low heat for about 4 hours until the meat is tender.
Keep checking in between. The way to know that the meat is cooked is when it breaks easily with a wooden spoon.
Dissolve wheat flour in half cup of water such that there are no lumps. Slowly add it to the gravy.
Stir to mix it well in the gravy and let it simmer for another 10-15 mins till the gravy thickens.
Sprinkle some lime juice and garnish with fresh coriander leaves. Serve hot.