Heat ghee in a large pan or kadhai and add all the whole spices.
Once they start sputtering, add the green chilies, ginger garlic paste and onions. Cook till the onions caramelize and become a light brown.
Add chopped tomatoes, all the ground spices except garam masala and salt to the pan. Saute till tomatoes have cooked through and start becoming pasty.
Add the minced lamb, garam masala powder, tomato puree, potatoes, green peas and one and a half cups of water. Bring this to a boil and then reduce the heat. Simmer till the potatoes are cooked through and most of the water has evaporated.
Check for seasoning and stir in chopped coriander. Top with lime wedges, butter and chopped coriander before serving.