In a separate large pan, heat oil over medium-high heat. Once hot, add the cumin seeds and sauté for about 15 seconds. Add the onions and sauté until slightly golden, about 7 minutes (See Note 2). Add the garlic and ginger and continue to sauté until the raw smell disappears (~30 seconds). Add the tomatoes and daal masala. Cook until soft and you see the oil leaving the sides, about 3 minutes.
Stir the daal into the tarka. Add 4 cup water (more or less), depending on how thick the dal got while cooking and how runny you like the consistency. Mix to combine.
Bring the dal to a boil. Once it comes to a boil, reduce the heat to low-medium so that it simmers. Use a slotted spoon to remove any white scum that rises to the top of the pan. Cover with the lid ajar. Cook, stirring occasionally, for 30 minutes (See Note 1), until the dal has no bite to it and can easily be mashed. Top with ¼ cup water if you feel the dal is getting too thick. Allow the dal to reduce and the flavors to meld for about 5 minutes, or until you achieve the desired consistency. Taste and adjust salt, if needed.
Add in the ghee or butter. Turn off the heat. Add lemon juice. Give it a stir.
Serve dal hot with rice, roti, naan or anything else your heart desires. I like to serve it with a mix of chopped onions, carrots, and cucumber on the side.
Note 1: The age of lentils will determine cook times. Older dried lentils can take up to 40 minutes on the stovetop, while very new may take 20-25 minutes. Treat cooking lentils is like cooking pasta. Just cook until they can easily be mashed, adding water if needed.
Note 2: At any point if the onions start to brown too quickly or the tomatoes or spices stick to the pan, deglaze with a splash of water.
Storage: Store in the fridge for 3-4 days and in the freezer for up to 3 months. Thaw and then (ideally) reheat over the stove. Depending on how thick the dal gets, you may need to add more water when reheating.
