In a mixing bowl, add urad dal, methi seeds, and moong dal. Rinse 3 to 4 times and add fresh water.
Cover and soak the grains for 5 to 6 hours.
Transfer to a blender jar, add water as required, and blend the soaked grains until smooth and bubbly.
Transfer the batter to a large bowl and add ragi flour, and water. Stir and mix the batter well until no lumps are seen.
Cover the bowl and allow the batter to ferment for 8 to 10 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 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)
On medium high heat, gently pour 1 ladle of batter and thinly spread the batter in circular motion.
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 with chutney.