Rinse the lentils well in a fine strainer under running water. Coarsely chop the spinach.

Transfer the lentils and spinach in a medium to large saucepan and add the water, salt, and turmeric. Bring to a boil over high heat. Cover, reduce heat to low, and cook, stirring occasionally, until lentils are tender, about 45 minutes. Remove from heat.

Mince the garlic. Heat the ghee in a small saucepan over medium heat. Reduce heat and add the asefetida, if using, and cumin seeds. As soon as they begin to sputter, add the garlic. Cook garlic until it begins to turn golden, about 1 minute. Add the chilies, paprika, and garam masala and briefly stir. Turn the heat off and pour the tarka (spiced ghee) over the dal. Stir well.

Chop the cilantro, if using. Scatter it over dal and serve with basmati rice if you like.