Wash the rice and lentils, change the water a couple of times.
Soak the rice and lentils in a bowl for 2 hours.
In a mixer jar, take the peeled onions, cumin seeds, curry leaves, dry red chilies, and pulse it for a couple of times.
Then, drain the water from soaked rice and lentil and add to the mixer jar.
Pulse it well and then grind to a smooth paste using water.
Transfer to a bowl, add salt, hing and mix well.
Heat a tawa and grease with cooking oil. Pour a ladleful of batter and quickly spread as a disc.
Drizzle oil over it and cook till the adai is cooked well.
You can either make thick dosas or thin dosas.
Serve with coconut chutney, spice podis.