1. Blend all the ingredients together. Add more buttermilk if necessary.
2. The batter should be relatively thin (pouring consistency). Salt to taste. Keep aside for 20 - 30 minutes.
3. Heat griddle to very hot, sprinkle some water till it sizzles and quickly pour 1 large spoon of batter on it. Spread by gently rotating the griddle. Lower the heat and when the edges begin to rise or brown, put some oil (1/2 tsp) over dosa, and trail some around it. When the edges begin to rise, ease out the dosa with the spatula under it.
4. Roll the dosa in a three-fold cylinder. Serve hot with onion and/or coconut chutneys. Lift with a spatula as for basic dosa.