Heat the oil in a heavy-bottomed pan; fry the onions till golden. Remove with a slotted spoon and keep aside.

In the same oil, fry the potatoes till light brown. Remove and keep aside. Add garlic paste, saute for 3 minutes. Add tomatoes and cook till the oil comes to the surface. Add the lamb, cumin powder, and turmeric powder; stir-fry for 6-7 minutes. Add enough water to cover the mixture; simmer till the lamb is 3/4th done.

Add potatoes, ginger, yoghurt, and salt. Cook for another 5 minutes.

In another large heavy-bottomed pot, put a layer of lamb (without the gravy) and potatoes, cover with half the rice. Crush and sprinkle part of the onions and half of the garam masala. Pour some gravy on top. Repeat this process a second time or till all the ingredients are used up. Now cook on low heat and place some live charcoal on the lid for 20 minutes. Alternately, this could also be done in an oven.

Sprinkle vetivier essence on top and mix thoroughly. Allow to stand for 15 minutes before serving.