Heat 4 cups of water in a pan.
Bring the water to a roaring boil.
Add the rice vermicelli into boiling water.
Cook for 5 to 8 minutes. (Cooking time of sevai will vary depending on the brand of sevai. Some sevais are very thin and does not take more than 2 minutes to cook)
When the sevai is cooked, turn off the heat.
Strain the sevai and keep aside.
Heat ghee in a pan.
Add mustard seeds, udad dal, dry red chilly, curry leaves and saute for few seconds.
Add cashew nuts and saute for few seconds.
Add chopped onion, chopped green chillies and saute till the onions turn soft and change its colour.
Add salt, sugar and mix well.
Now, add the cooked sevai and give a gentle mix.
Add grated coconut, chopped coriander leaves and give a mix.
Rice Vermicelli Upma is ready to be served.