Powder the rolled oats coarsely in a blender. Wash and chop the celery sticks and puree it along with the dried red chillies.
Mix together the oats, semolina, pureed celery, salt and bicarbonate of soda in a large bowl.
To prepare the seasoning heat the oil in a pan, add mustard, urad dhal, cumin seeds and cashew nuts. When the dhal and nuts are light brown in colour, add the seasoning to the flour mixture and mix well.
Now add the yogurt, buttermilk and finely chopped coriander leaves and mix well to make a batter. Immediately pour the idli batter in the greased idli moulds and steam it. This would be a perfect breakfast or dinner with coconut almond chutney .