1. In a large bowl, mix idli rawa and sabudana supermeal together.
2. Add yogurt to it and add 2 cups of water.
3. Mix well along with salt until blended.
4. Cover and set aside for around 1 hour.
5. Give it a good mix, consistency of batter should be like heavy pour... feel free to add a little bit of water if required
6. In a pan, heat some ghee - 1 tbsp or so. Add mustard seeds when it starts popping, add curry leaves and add it to the batter along with roasted cashews, baking soda and cilantro(or any vegetable you care to add).
7. Mix it well and when blended, drop ladleful of batter to your Idli moulds.
8. Steam them around for 20 mins, or until the fork/toothpick inserted in the middle comes out clean.
9. Allow it to cool for a few minutes and then remove from the mould.
10. Serve immediately along with any chutney of your liking. I served it with green mint chutney.