Rinse all ingredients (raw rice, idli rice, urad dal, channa dal, javvarisi, fenugreek) 2–3 times.
Soak them together for 4 hours.
After soaking, drain the water completely.
Add a handful of ice cubes to the mixie jar (helps prevent heat while grinding).
Grind the soaked ingredients in batches using ice cubes or chilled water until you get a smooth, fluffy batter.
Transfer the batter to a large bowl. Add salt and mix gently with clean hands.
Cover the bowl and allow the batter to ferment for 8 hours or overnight, depending on weather.
After fermentation, the batter will rise and look airy. Mix gently once.
Adjust the batter consistency with a little water — it should be flowing, not thick.
Heat a dosa tawa. Pour a ladle of batter and spread it thin in circular motion.
Drizzle oil around the edges and cook until the dosa turns crispy and golden.
Serve hot with chutney or sambar.