Wash rice and moong dal changing water 3 to 4 times, drain the water. Use the pressure cooker to save time. In preassure cooker add rice, beans, potatoes, salt, turmeric, clarified butter, and 3 cups of water.
Close the pressure cooker and seal the exhaust, or put the weight. Cook over high heat.
After the pressure cooker start steaming lower the heat to medium and cook for about 4 minutes.
Turn off the heat and wait until steam has stopped before opening the cooker.
Mix the khichdi well, dal and rice should be very soft, little mushy.
Heat the clarified butter in other saucepan over medium heat, Test the oil by adding one cumin seed to the oil; if it cracks right away oil is ready. Add the cumin seeds, black mustard seeds, and asafetida as seeds crack add tomatoes, green chili, ginger, salt and red pepper stir.
Let tomatoes cook over medium heat until they are tender and mushy. This should take about 6 to 7 minutes. Lower the heat to low. Add cilantro and garam masala, stir for a minutes.
Add cooked rice, mix gently, and add hot water slowly as needed. Consistency of the khichdi should be like runny dough. Note: as khichdi cools will become little thick.
Serve khichdi hot, and serve the khichdi with pickle, yogurt and papdam.