Wash dal. Place legumes in a bowl & cover with hot water. Soak for 2 hours, drain & rinse. Put in a large pot with the turmeric, ginger, garlic, chilies & 3 cups water. Boil & simmer for 45 minutes. Turn off heat & let cool slightly. Puree with a wire whisk. Heat ghee in a deep pot & add mustard seeds. Fry for 15 seconds. Add cumin seeds & cook for 10 seconds. Add asafetida & cook for a second or two, then add the tomatoes. Cook, stirring rapidly, for 3 to 4 minutes. Add eggplant & zucchini & cook for an additional 3 minutes. Add lentil puree & salt & bring to a boil. Reduce heat & cook covered for 20 minutes. Serve over plain rice. *Use a mixture of dals, yellow lentils, pink lentils, yellow split peas & yellow split mung beans. Julie Sahni, "Classic Indian Cooking"