Mix semolina, rice flour and all purpose flour in one bowl.
Add water and mix well.
Now add rest of all ingredients except onion and add more water. Cover it and keep aside it for 15 minutes.
After 15 minutes semolina is soaked properly and may need to add more water. Our batter should be very thin and runny.
Heat skillet,add few drops of oil and spread it with samp cloth or tissue. Sprinkle onions on skillet.
Then after few seconds, stir the batter, take a laddleful of batter and add onto skillet. Add few drops of oil around the sides and on the top too.
Let the dosa cook on medium flame till it becomes crispy. Serve hot with chutney.
