firstly, in a large bowl soak 3 cup idli rice and 1 tsp methi for 5 hours.
also, soak 1 cup urad dal for 3 hours.
drain off the urad dal and transfer to the grinder. you can use mixi if you are comfortable.
grind to smooth paste adding water as required.
after grinding for 40 minutes, the batter will turn soft and fluffy.
scoop out urad dal batter and keep aside.
in the same grinder add soaked rice and 1 cup poha.
also, add water as required and grind the batter.
grind to a slightly coarse batter. if you grind to a very smooth paste, then the dosa will be very soft and not crisp.
transfer the batter to the same vessel of urad dal batter.
mix well making sure everything is well combined.
cover and allow to ferment for 8 hours in a warm place.
after 8 hours, the batter would have doubled indicating its well fermented.
now mix the batter gently and use the batter to prepare dosa.
finally, the dosa batter can be stored in the refrigerator for up to a week and use to make weeks breakfast.