Heat a pan with oil. Add mustard seeds and let it pop.
Add onions, green chilies and saute till the onions turn translucent.
Add chopped keerai thandu. Drain the water from moong dal and add the dal to the pan.
Add salt, mix well and close the pan with a tight fitting lid and let it cook over low flame for 5 to 7 mins.
Add red chili powder, sprinkle a handful of water, mix well and close the pan with a lid. Cook over low flame for 2 to 3 mins.
Add curry leaves, fresh grated coconut and toss well. Switch off stove.
Keep the pan closed for another 2 more mins for the flavours to merge well.
Keerai thandu poriyal is ready.
Serve as a side dish with any rice of your choice. You can also mix this with rice and eat it with a pappad.