Break potato in small pieces. Not grate them. Heat pan and add 1 tsp of oil.
Add hing,mustard seeds and cumin seeds and let them crackle. Add green chilly, curry leaves and saute them.
Now add turmeric powder, chilli powder, dry mango powder, ginger garlic paste. Add boiled potatoes, salt and mix well.
Now add coriander leaves and mix well . Potato mixture is ready , transfer it in a bowl and let it cool down.
Now take gram flour in a bowl, add soda, salt and mix well. Now add little water at a time and make smooth thick dough.
When potato mixture is cold, grease hands with oil. Now make small golf size bowl.
Heat the appam pan and add 1/4 to 1/2 tsp of oil in each hole. Dip potato balls in gram flour mixture and put them in pan.
Cover the pan and cook them for a minute. Turn them over and cook till they are golden brown and crisp from both side.
To serve take a pav and slit it from the center. Apply vada pav chutney and put a vada inside.