Wash and soak the puffed rice separately. Soak rest of the ingredients (except salt) together for 6 hrs.
Once ready to grind, drain the puffed rice and add first to the grinder. Run for a couple of times for it to get ground smooth.
Then add the drained rice and continue grinding to a smooth batter, making sure you add just enough water.
Once the batter is ground to a soft texture, add salt and let it ferment overnight.
If you are going to make dosas right away, proceed to make, else you can refrigerate the batter.