Soak the rice and dal with a handful of menthya and chana dal overnight. Grind both soaked stuff to a smooth paste in a blender. Mix the batter well in a large steel bowl. Place the batter in a warm place(say, oven) to ferment overnight. Keep a big plate underneath the bowl, because fermentation may cause the batter to overflow.
Place the griddle(pan) on the medium-high set stove top. Let a pan heat up on the stove. Sprinkle some drops of water. After they evaporate, pour a big ladle of batter and spread it in a circular fashion. Pour 1 tsp of ghee/oil along the edges. Cover it. After 2 or 3 minutes turn over the dosa and wait for 2 more minutes so that it is well done on both sides. Place the dosa on to a serving dish. Serve with Potato curry and coconut chutney.