First take a big bowl,add in rava and curd and mix well,now add water and soda and keep mixture covered for at least 10 mins.prepare all the spice mixture for TEMPERING (pic3)

Heat oil then add curry leaves,split chickpeas,cuminseeds, mustard seeds,ginger,garlic paste,saute few seconds then lastly add coriander leaves and green chilli and mix well and temper the batter.mix well,now apply oil and pour 2 tbsn batter into each bowl of idli steamer

Steam batter for at least 10 mins.let it cool a bit and remove and serve hot with green coconut chutney.