In a bowl soak Rice for 8 hour (or overnight)
In another Bowl Soak Urad dal for minimun 3 hours.

If you have methi dana add it to rice while soaking if not
then add chana dal to urad dal while soaking.

Drain and wash Urad dal and grind it to smooth paste til
fluffy.

Drain and wash rice and grind rice and methi dana with
required amount of water.

Mix well both the batters together and allow it to ferment for
minimum 8 hours in a warm place.

If you are living in a cold place or the weather is cold
then keep it in preheated oven.

After 8 hours Batter will get fermented and take the required
amount of batter you want to use add sugar (1/2 tablespoon)
and salt (1/2 tablespoon) to it and mix well.

Heat skillet and on a medium to low heat sprinkle water
and wipe out.

Pour a ladle full of batter on it and spread in round motion.

Let it cook for few seconds. then spread Onion chutney on it and then prepared Masala (potato stuffing) on oneside of it.

Cook till the bottom of dosa turns golden brown.

Now Fold over to it to half by making a semi-circle and serve hot with coconut chutney/ peanut chutney/ onion chutney and sambar.