Wash thoroughly and soak black gram and rice separately for 6 - 8 hrs.
Grind them separately into very smooth paste and mix them together adding salt.
Allow this dough to ferment overnight during winter and 4 to 5 hours in summer.
For the stuffing (masala):-4)Boil potatoes and chop onions, ginger, garlic and green chillies may be finely chopped or made into paste.
Heat oil in a broad pan.
Add a tsp of black gram, mustard and red chillies.
When mustard seeds splutter, add cumin seeds, onion pieces, ginger garlic and green chillies (finely chopped or ground), turmeric powder, curry leaves broken into pieces and fry till transparent.
Meanwhile, peel the boiled potatoes and cut them into medium size pieces.
Add them to the frying onions, mix well, remove from fire after about 5 mins and set aside.
Make the chutney by grinding together 1/2 coconut, 4 green chillies, 1 tsp of ginger, a bunch of cilantro, tiny piece of tamarind and salt to taste into fine, thin paste, adding water.
Heat a flat pan and make thin dosas by spreading the dough on the pan with a ladle.
Spread oil all around the dosa and when the edges turn golden brown, don`t over turn the dosa but place two table spoons of the prepared masala on the dosa and first fold one side over it and then the other side and remove from pan and serve.
Repeat the procedure for the next dosa.
:- The secret of crisp dosas lies in the amount of oil spread around it. With chutney these masala dosas make great eating.