Let the ghee (clarified butter) melt in a small saucepan over medium-low heat. (Ghee is the traditional Indian choice, but you can substitute butter and a splash of olive oil if you can't find ghee). Once the ghee begins to sizzle, add the cumin seeds and stir for about 5 seconds. Add the onion and saute until it's slightly soft, 2 to 3 minutes. Add the garlic and cook for 2 minutes. Add ginger and jalapeno and cook one minute longer. Add the spice mixture you made in Step 1, then the pureed tomatoes. Mix, then put a lid on the pan and let everything cook down, 5 to 10 minutes.