The traditional way of making yellow daal is a two step process. The lentils are cooked separately. Meanwhile, you make a “tadka” with minced onion, ginger, garlic, spices and in some recipes also tomato.
Wash and drain lentils. Heat cooking oil in a large pot on medium heat. Add cumin seeds and sizzle for 30 seconds. Add tomato, cook for 3 minutes to break down the pieces.
Add lentils and water. Cover and bring to a boil, watching closely to prevent it from boiling over. Add turmeric, salt, and other spices. Reduce heat, cover just loosely to prevent daal from boiling over. (Note: Adding a bit of butter [1 Tb] helps to prevent this). Simmer for 20 minutes, stirring once or twice. Add green onion, cook for another 5 minutes. Add fresh cilantro. Turn off heat.
Enjoy as a soup by itself OR serve with basmati rice pilaf.