Heat ghee in a large pan over a medium heat. Add the pepper, cardamom, cloves, and mace, and fry for 1 to 2 minutes, or until the spices are sizzling and fragrant.
Add the onion, and fry for 8 to 10 minutes, stirring regularly, or until golden brown.
With a slotted spoon, transfer the lamb pieces, and fry for 3 to 4 minutes, stirring continually, until the lamb pieces are slightly browned.
Add the garlic and ginger pastes and stir to combine. Reduce heat and cook for another few minutes.
Stir in the ground coriander, cumin, red chile powder, fennel seeds, garam masala, tomato pulp, yogurt, and salt, to taste. Cover the pan with a lid, and then reduce the heat to low, and simmer for 10 to 12 minutes, or until the sauce has almost completely dried out.
Add about 1/4 cup of strained broth from the pre-cooked lamb dish and simmer until the volume of liquid has reduced and the sauce has thickened.
Add enough of the strained broth from the pre-cooked lamb (I used it all) to almost cover the lamb, and bring the mixture to a boil, then reduce the heat to a simmer, and cook for 8 to 10 minutes, or until the gravy has thickened.