Pressure cook moong dhal for a whistle and keep aside.
Heat oil in a pan, add mustard seeds, let it splutter.
Now add urad dal, curry leaves and hing.
Add onions, green chillies, and saute till it turns slightly browned.
Add the beans and saute for 3mins.
Now sprinkle water and allow it to cook.
Keep closed in medium flame until beans becomes soft, and then add salt to taste.
Keep in low flame to avoid burning.
Once beans is cooked add moong dal and give a stir.
Add coconut and switch off.
Serve Beans Poriyal with rice!