Take leftover idlis and make into pieces. If it's kept in fridge it will be easily made into pieces by crushing it.
Heat oil in a wok and add mustard seeds, urad dhal, bengal gram and dried chillies and saute till onions are transparent. Add idlis to it and salt to taste. Saute for a minute and cover the wok and sim the flame.
Add curry leaves and give a stir. Idli upma is ready to serve. Easy and quick recipe to make.