Preparation for potato filling
Rinse and boil potatoes in 2 cups water for 5 to 6 whistles in a pressure cooker or till the potatoes are completely cooked.
Whilst the potaoes are cooking soak the chana dal in hot water for 30 minutes. Then drain the water and keep aside chana dal.
When the pressure settles down on its own in the cooker remove the lid. Drain the water completely and let the potatoes cool down a bit then peel them, chop them and keep aside.
Also slice the onions thinly and chop the green chilly, ginger and coriander leaves.
Making potato filling
In a non stick pan heat oil on medium flame setting and fry cashews.
After cashews are lightly fried shut the gas and keep the fried cashew aside.
In the same pan on the lowest flame setting fry mustard and once they splutter add chana dal.
Saute the chana dal for 2 to 3 minutes on the lowest flame setting till they turn light golden or golden. Now add the sliced onions,
curry leaves, green chilies and ginger and saute till the onions are softened and turned translucent.
Add the turmeric powder and mix very well.
Add water mix well and simmer for 2 to 3 minutes or till the mixture thickens a bit.
Add boiled chopped potatoes and mix very well.
Add salt and mix very well.
Simmer on the lowest flame setting for 3 to 4 minutes stirring continuously so that the mixture doesn\'t burn or stick to the pan.
Stir continuously till the water reduces and the potato masala thickens.
Switch off the gas and add chopped coriander leaves, fried cashews and mix well.
The potato filling should be moist and easily spreadable on the dosa.
Make sure there is no water in the potato masala. It should not be of a curry or gravy consistency.
Stir and keep the potato masala aside.
When dosa is ready place the dosa in a serving plate open faced. Add a portion of the potato filling on the dosa. You can spread it a bit if you want.
Now fold the dosa and serve hot with coconut chutney and sambar.
Potato filling for 8-10 dosas (depending on the size of the dosa and filling)