Firstly to prepare the filling for the dosa heat oil in a thick bottom pan. Once hot reduce the flame and add mustard seeds, curry leaves, and green chilies.

Once the mustard seeds start to splutter and there is a nice aroma add the sliced onions and chopped ginger.

Once the onions start to turn translucent, add tomatoes. Saute for 2-3 minutes and then add turmeric and salt. Cook well until the tomatoes get smashed and start leaving oil.

Now add the mashed potatoes and mix everything well. After cooking for 2-3 minutes it's done, now keep it aside and let it cool.

Now on a flat dosa pan, spread the dosa batter and make evenly thick dosa by applying ghee.

Once the dosa is done remove from a plate Place some potato batter in between n spread and make roll

Your yummy masala dosa is ready to Serve.