1. Dry roast the yellow moong dal till it turns slightly brown.
2. After it cools down a little bit, wash and soak along with the one cup brown rice. Let it soak overnight.
3. In the morning, grind it to a smooth batter and let it sit for an hour or so.
4. Heat oil in a small pan, add hing and roast for about 10 secs. Add the mustard seed, curry leaves and red chillies.
5. Fry for 1 minute and add it to the batter.
6. Add the eno to the batter and mix it combined.
7. Steam the idlis for 10-12 minutes and serve hot with chutney or sambhar.