First add salt as per your taste to the batter.
Place the potatoes in a large saucepan, cover with water ,and set over medium heat.
Bring to a boil , then reduce the heat to medium and simmer for about 20 mins, until the potatoes can be pierced with a knife. Drain , reserving about 1 cup of cooking water.
Let potatoes cool slightly, then remove the peels with your hands and place the potatoes in a large bowl.
Temper the spices: wipe clean the pan used to cook potatoes . Heat the oil over medium- high heat until very hot but not smoking
One immediately after the next , add spices without stirring: first the mustard seeds(they will start to pop), followed by cumin seeds, then red chillis , channa dhal, urad dhal, curry leaves , and asafetida.
Let the spices darken a couple of shades , taking care not to let them burn .
Reduce the heat to medium and add the onion, cashews, if using, ginger, and green chilies. cook, stirring often until the onion is glossy and slightly softened , about 2 minutes. Add turmeric and cook for 30 seconds, then add salt.
Return the potatoes to the pan and coarsely mash with a potato masher until they are bit coarser and drier than chunky mashed potatoes.
stir in some of the reserved potato cooking water to moisten and break down the potatoes to a scoopable consistency and add lemon juice to taste.
Now make a delicious crêpe dosa with our Crêpe dosa batter (check out the video how to make crêpe dosa) and serve stuffed potato masala into your dosa and Enjoy!