Thoroughly rinse the toor dal by scrubbing the pulses under running water. Place in a medium saucepan or wok and soak for 2 to 3 hours in 2 cups of water. Add the turmeric and bring to a boil. Turn the heat down to medium and cook, partially covered, until the dal is tender — about 20 to 30 minutes. Stir in the spinach, replace the lid to partially covered, and continue to cook until the spinach is cooked and most of the liquid is gone. Turn off the heat and let the dal and spinach sit.
Heat the ghee, butter or oil over medium heat in a frying pan. Toss in the chilies and ginger and fry, stirring frequently, until the ginger just begins to brown, about 5 minutes. Stir in the garam masala, then add the asafoetida, stir once, and pour the seasonings into the dal and spinach. Stir in the lemon juice and salt.
Serve hot or warm on a bed of white rice.
