Rinse and soak rice flakes for about 10 minutes before grinding. Next take drained lentils in a mixer and grind finely adding water as needed.
Transfer the lentil batter to a wide bowl. Next take soaked dosa rice in the mixer and grind it finely as well.
Transfer the rice batter to same bowl. Finely add soaked rice flakes and grind it to fine batter. Transfer this also the bowl. Mix everything well.
Let this batter ferment for about 8 to 10 hours at warm place. After fermentation the batter would have raised. Add salt and rice powder to it. Mix well and the batter is ready.
To make chutney, take all the ingredients under "For chutney" list and grind coarsely. Chutney for benne dosa is ready.
Next heat a pan adding oil, mustard and cumin seeds. As they splutter add curry leaves and sliced onion. Saute till onion turn translucent. Then include green chillies, mashed potato and salt. Mix them well.
Next heat tawa and smear some oil over it. Sprinkle some water and wipe it off. Pour a ladle full of batter at the center and spread like dosa. After 10 seconds, apply butter generously all over the dosa and let it cook.
When it cooks to slightly brown, loosen the edge and remove from tawa. Turn the dosa and cook for 2 seconds. Remove and serve hot with chutney and masala.
Repeat the process with rest of the batter. Benne dosa Yum!