Ingredients:

1 cup - rava/sooji/semolina
1/2 cup - curd (sour or not sour depending upon your taste)
1 tsp - Eno fruit salt (plain or lemon flavor)
1/2 tsp - lemon juice
1 tsp - ginger (chopped very fine or paste)
4 - green chillies (chopped very fine or paste)
1 tbsp - curry and coriander leaves (chopped very fine)
1/2 cup - water (adjust to reach consistency)
Salt as needed

To temper:
1 tsp - mustard
1 tsp - urad dal (Ullutham paruppu
1 tsp - channa dal (Kadala paruppu)
1 tbsp - cashews (broken into small pieces)
1 tbsp - oil and ghee

To garnish:
1 tbsp - carrot, grated
1 tbsp - coconut gratings

Method:

Heat a kadai and add ghee and oil, splutter mustard and add the rest of the ingredients under the to temper table.
Then add the finely chopped ginger and chillies (alternatively, you can grind ginger and green chillies and use the paste too).
Then add the sooji with curry leaves and coriander leaves to it and fry on a low flame taking care not to change the colour of rava.
After two mins, transfer to a bowl, cool down and add the curd, enough water, lemon juice, salt and mix well (the consistency should be like our idly batter consistency, light and not too thick)
Heat the idly cooker with water and let it be just ready for steaming and grease the idly plates with ghee/oil.
At this time add the ENO salt to the batter and mix well (the eno salt should be active enough, so that when you add and mix the batter, small bubbles appear, which make the batter frothy)
Immediately, pour into the idly moulds and steam for 5-7 minutes (to check if it`s done, insert a knife or spoon back and it should come clean)
Your spongy, moist, soft rava idlis are ready now!
Garnish if desired and serve with coconut chutney.
Makes 10-12 idlis

Recipe courtesy: Rak`s Kitchen
http://rakskitchen.blogspot.com/