Add the rava to a heavy-bottomed pan and roast it on low-medium heat until it becomes aromatic and lighter, about 6-8 minutes. The rava should not get brown or golden, so stir it continuously.
Transfer the roasted rava to a mixing bowl and allow it to cool. Once it cools to room temperature, add yogurt, salt, green chilis, ginger, and cilantro. Mix well to prepare a batter.
Heat ghee or oil in a pan and add chana dal and urad dal. Roast the lentils until they are light brown. Add mustard seeds, curry leaves, and cashews. Stir well and fry until mustard seeds start popping.
Turn off the heat, add the tempering to the batter, and mix well. The batter should be of the same consistency as the regular idli batter, not too thick or too thin.
If your batter is too thick, add more yogurt or water until you get the right consistency. Cover the bowl and allow the batter to rest for 10-15 minutes.
While the batter is resting, add 2 to 2½ cups of water to the steamer and bring the water to a boil.
Grease the idli plates with oil or ghee.
Once the batter is rested, recheck the consistency as the rava absorbs the water. If it looks very thick, add 1-2 tablespoon of water to adjust the consistency.
Sprinkle 1 teaspoon ENO over the batter. Quickly but gently mix well.
Pour the batter into the idli molds and place the idli stand in the steamer. Cover the steamer and steam the idlis for 10-12 minutes or until done. To check the doneness, insert a skewer or toothpick in the center, which should come out clean.
Remove the idli plates and allow them to rest for 2 minutes. Carefully remove the idlis with a knife or spoon.
Serve the hot steaming rava idlis with your favorite accompaniments.