Spinach and Tomato Dal (Indian Lentil Soup)

Bring lentils and 4 cups water to a boil in a saucepan. Stir in salt. Reduce heat to medium-low and cook at a simmer 10 minutes. Skim off any scum that forms and continue to simmer until the lentils are tender about 1 hour.

Heat the oil in a separate saucepan. Cook mustard seeds and cumin seeds in hot oil until they start to splatter 2 to 3 minutes. Add onion garlic and turmeric to the seeds; cook and stir until the onion is soft about 5 minutes. Stir spinach tomato and cayenne pepper into the onion mixture; cook until the spinach wilts and the tomato is tender about 5 minutes.

Stir the cooked lentils and cilantro into the spinach mixture; bring to a simmer and cook for 5 minutes. Adjust salt and water to taste and texture preferences.