First rinse and then boil potatoes. The potatoes have to be completely cooked. Once it's done, drain it off and let it cool. Then peel and crumble the potatoes. Secondly, heat a pan with oil. Add mustard seeds, chana dal, curry leaves and onions. Once it's turns brown, add green chilli, ginger-garlic, turmeric and gram masala. Add salt to taste.

For making coconut chutney, add grated coconut, three green chilies, curry leaves, roasted chana dal or pottukadalai into a blender and blend to get a smooth chutney. Add water little by little while grinding. Then heat a pan with oil and add mustard seeds, urad dal, chanadal, curry leaves till it becomes brown. Then add coconut chutney into the pan and stir it well for a minute. Then turn it off.

Now, let's make dosa. Heat the tawa and sprinkle few water on the tawa. Though it's a readymade dosa batter, kindly add salt and then stir it well. Once the tawa is heated, then add batter on the tawa and spread it to a even round dosa. Add oil and after few minutes, add potato masala on it and spread them.

Within few minutes, you can see the edge leave the pan. Then fold the dosa and serve.