In a large bowl, add idli rice, urad dal, and methi seeds. Rinse 3 to 4 times and add fresh water.
Cover and soak the grains for 5 to 6 hours.
Wash and soak poha before grinding the above ingredients. Soaked Poha or flattened rice helps make soft and spongy set dosas.
Blend the soaked grains along with soaked poha until smooth and bubbly.
Transfer the batter to a large bowl. Stir and mix the batter well.
Cover the bowl and allow the batter to ferment for 8 to 12 hours. During the cold days, allow the batter to ferment in the preheated microwave for 8 - 10 hours(Preheat the microwave for 2 minutes).
After fermenting, the batter is almost doubled. Add salt and mix well.
Heat a griddle or iron tawa on medium heat and spread some oil in a circular motion ( I use a fork and an onion halved in half to spread the oil. I have seen my grandmother and my mom using this method for decades on cast iron tawa to avoid sticking)
Gently pour 1 ladle of batter and slightly spread to form a small and thick dosa.
Sprinkle some oil. Using a stainless steel spatula, flip the dosa when holes ( air pockets) are formed.
After a few seconds flip again and serve hot set dosa with chutney and sagu.