Add idli rice, grated coconut, ¾ cup of water and salt to a mixer and grind to a smooth paste.
Transfer the paste to a bowl and add 1 ½ cup of water and mix well. Adjust the consistency with the remaining water if necessary.
Heat a non-stick pan and brush it with ghee.
Pour a ladleful of batter and swirl it around till the base is covered.
Cook for 30 seconds and then cover and cook it for 30 more seconds on low. Remove the lid and cook for another 15-20 seconds.
Once you start seeing the edges leaving the pan, the dosa is ready. Slide it out on a perforated surface like a sieve. This allows it to cool completely without becoming sticky.
Fold into a triangle and serve.