In a blender, combine garlic, green chili, and ginger. Blend to make a paste.
Fry the onion in ghee until light brown.
Add the ginger chili paste to onion and stir for 1 minute on medium heat.
Add the lamb and rest of spices, stir for 10 minutes on medium heat.
Pour the coconut milk over the lamb, add enough water to cover the lamb completely.
Let it simmer for one hour, adding more hot water if required.
When the lamb is done add the vinegar and cook for 20 minutes.
You should have thick gravy and you're done.