Roast the oats for 2-3 minutes in a dry pan. Allow it to cool and powder it in a mixer. Dry roast the rava till it turns golden brown and keep it aside.
Heat 2 tablespoons of oil in a pan, add mustard and after it splutters; add cumin, channa dal, urad dal and saute for a few seconds. Add onions, green chilli, ginger, curry leaves, coriander, Asafoetida Powder and saute for 2 minutes, turn off the stove.
Mix powdered oats, roasted rava, curd, salt, cooking soda, some water and prepare a thick batter. Add sauteed ingredients, grated carrot and mix it.
Grease the idly plates, spoon the batter into the greased plates. Steam it for 10-12 minutes in medium heat. Serve with Chutney and Sambar.