Grind 1 cup oats into a coarse powder and keep it aside.
Heat 1 tablespoon oil in a pan, add mustard seeds and allow it to splutter.
Add chana dal, Urad dal and broken cashew pieces and fry well , till it starts to brown lightly.
Add ½ cup fine sooji/rava and fry well for 2-3 minutes on a medium heat.
Add oats powder and continue to fry along with sooji for another 2-3 minutes. Turn off the heat.
Add ¼ teaspoon Asafoetida, ¾ teaspoon salt and ½ teaspoon Baking Soda (cooking soda) and mix well.
Add chopped coriander leaves, curry leaves, green chillies, grated carrot, and grated ginger and mix well.
Add ¾ cup water and ¾ whisked curds mix well and allow it to sit for 15 minutes.
Mean while, grease the Idli plates and boil the water in steamer / pressure cooker/idli maker.
Using ladle, Pour ¾ of idli batter into the idli moulds, and place in steamer /pressure cooker /idli maker.
Cook for 12 minutes and give a resting time of 5 minutes.
Remove the idlis and serve hot with Coconut chutney ,sambar or Bombay saagu