Add the cooked and mashed dal to the skillet. Reduce the heat to low and cook for 20-25 minutes. Keep stirring at regular intervals. Add some water if the dal is too thick and bring it to a boil.
Dal makhani can be stored in a clean and dry airtight container in the refrigerator for about 4 to 5 days. It is freezer-friendlytoo. Freeze it for up to 3 months in freezer-safe containers.