In a pan add 2 to 3 tsps of oil. When the oil gets hot, add the mustard seeds. When the mustard starts popping add the cumin seeds, curry leaves, red chili, garlic, ginger (if using). Fry for 30 seconds.
Add the chopped onion and cook till soft. Add the asafetida and mix.
Transfer the tempering to the cooked dal mixture.
Add necessary salt and adjust the water as per your choice.
Cook the pappu in medium flame for ten minutes.
Finally garnish with coriander leaves.
Serve the tangy mamidikaya pappu with annam (rice), ghee, a stir fry and pachadi.