In a non stick pan, dry roast the vermicelli till nicely done. Ensure it doesn't get burnt.
Remove and in the same pan, heat oil, add the onion pieces. I add them in big chunk so that kids can throw them off easily! Then add the green chillies, curry leaves.
Once the onions are turning pink or translucent, add the salt along with water. When the water starts boiling, add the roasted vermicelli and mix well.
Cover with a lid and simmer for 5 more mins. Since you are adding 1 cup of water, ensure it gets cooked in low fame. When you find that water is completely evaporated which is about 5 - 6 mins, switch off and remove.