Soak rawa in curd, adding enough water so that it resembles a typical idli batter. The consistency has to be neither too thick nor too thin. A semi pouring consistency would be ideal.
Allow the batter to ferment for over 8 hours. (Fermentation makes the batter lighter and releases good bacteria, which is good for the human gut.)
After the batter is fermented, add whole wheat flour (aata) and powdered poha to the batter. Aata helps to bind the sooji and poha adds texture. In case you do not have poha, you can add powdered kurmura. A friend of mine would add saboodana powder for texture.
Heat oil in a pan, add mustard seeds, hing, broken cashew nut pieces, curry leaves and let it crackle.
Pour the tempering/tadka over the batter. (You can even add urad dal to your tadka. In case, you or your little one is fond of raisins,you could add them too. If you dislike the idea of adding dry fruits to your idli batter, you can avoid that. You need not even add tadka to your batter. Instead add some warm oil to your batter. The oil prevents your idlis from getting sticky.)
You can even add boiled vegetable purée to your batter. Boiled carrot purée, palak purée, beetroot purée will make your idlis look colorful and attractive. In case, you have kids who love to eat their vegetables, you can add grated carrot, bell peppers, sweet corn, chopped palak, chopped methi, grated broccoli and just about any vegetable your child loves. (Shweta used spinach and carrot purées to get the tricolor effect.)
Add salt to the batter.
Steam the idlis.
After the idlis are steamed, allow them to cool a little before demoulding.
Serve hot along with sambhar, chutney, or any favorite dip. (Shweta served the idlis with tomato, carrot, and onion chutney.)