In a pan, add the oil. Once hot, add the cumin seeds, bay leaf, and open the cardamoms and add them and then add add ginger garlic paste as well. Let them sizzle. Add the butter, once it melts well add the chopped onions and salt. Stir well and cook in medium flame until light golden. Then add in the tomato puree. Stir and cook for about 15 minutes or until it leaves the sides.