Dry roast oats for 4~5minutes. Cool and then grind to a find powder.
Heat 2tsp oil in a pan; add mustard seeds and once the seeds start to splutter, add the remaining tempering ingredients. As the dal starts to change color, add grated carrot, green chilies. Cook for 2 minutes stirring.
Next add semolina and cook for 4~5 minutes. Turn off the heat and add the roasted oats. Mix well and let cool for 10 minutes.
Add yogurt, salt and enough water to make a thick batter. Mix in baking soda.
Grease idli plates and pour 3~4tbsp batter in each depression of the plate. Steam for 13~15minutes.
Serve hot with chutney of choice and/ or sambar.