firstly, in a large mixing bowl soak 3 cup dosa rice and ½ tsp methi for 5 hours. alternatively, use idli rice / sona masuri rice.
in another bowl soak 1 cup urad dal for 3 hours.
drain off the water from urad dal and blend to smooth paste adding water as required.
transfer the smooth and fluffy batter of urad dal into a large bowl.
in the blender take soaked rice draining off the water.
bend to a slightly coarse paste adding water as required.
transfer the rice batter to the bowl of urad dal batter.
now take 2 cups washed & squeezed puffed rice in a blender.
and blend to smooth paste. alternatively, use leftover rice or soaked sabudana.