Heat the oil in a pan and add the cashew and fry for a minute.
Add the ginger and green chilly and fry for 30 seconds.
Now add the rava, mix well and roast the rava for three to four minutes. Remove and set a side.
Now add the vermicelli to the pan, and fry this till pale brown. Keep mixing to avoid burning.
Set a side to cool completely.
In a bowl add rava, vermicelli, coriander, grated carrot and salt. Mix well.
Now add the yogurt and water. The batter will be semi thick.
Set a side for 15 minutes.
After 15 minutes, mix the batter. You may want to add little more water if the batter is too thick. The batter should be of idli batter consistency.
Add the baking soda and give a mix.