1. Grind the oats into a fine powder.
2. In a bowl, mix the oats powder, rice flour, semolina, yogurt, and water to make a smooth batter.
3. Add salt, cumin seeds, chopped onion, green chili, and coriander leaves to the batter. Mix well.
4. Heat a non-stick pan and grease it lightly with oil.
5. Pour a ladleful of batter onto the pan and spread it in a circular motion to make a thin dosa.
6. Cook on medium heat until the edges start to lift and the dosa turns golden brown.
7. Flip the dosa and cook for another minute.
8. Serve hot with chutney or sambar.