Heat up a pot and add a few tbsps oil. When the oil is hot, add cumin seeds. They’ll sizzle and turn color in just a few seconds. Add the onion, 2 pinches salt, and sauté for a minute. Then add the garlic, ginger and green chiles. Sauté until golden brown.
Add the coriander, turmeric and chili powder. Stir for 10 seconds. Add the tomato puree, stir and cook until oil separates. Add 1/2 tsp salt. The mixture will get a little thick. Add the ground lamb, break up the meat and mix. Add 1/2 cup water and it'll be easier to mix the meat.
Cover and cook for 15 minutes or until the lamb is tender. Since it’s ground meat, cooking time is short. Stir during cooking and add a little water if necessary. When the lamb is almost done, add garam masala, cover and cook for two more minutes. Taste and adjust salt.
Don’t cook it any longer, you want it to be thick but not dry. It should have some moisture. You can add a teaspoon or two of lemon juice if you like. Chopped cilantro leaves are a nice addition.