Heat a small frying pan with 2-3 tablespoons of the oil. When hot, add the mustard seeds and wait until they splutter
Then add the curry leaves, hing, ginger, garlic, chilis and turmeric
Fry this well for 2-3 minutes or until the raw smell of the ginger and garlic goes away. Remove from flame
In a mixing bowl, take the potatoes and pour the fried ginger and garlic mixture into it, along with salt and the chopped coriander leaves
Mix well so that everything is well incorporated. Divide this mixture into equal sized balls
In another bowl, whisk the gram flour with a touch of salt and add water gradually to form a lump free and moderately thick batter**
Set the kadhai with the oil to heat. Add a tablespoon of the hot oil to the besan batter and mix well - this results into crispy vadas
Dip the spiced potato balls in the gram flour batter, coat well and deep fry them over moderate heat, until golden brown all over
Remove and drain the batata vadas on kitchen towels
In the same oil, fry the large green chilis for 30 seconds each. Remove on kitchen towels and drizzle some salt over them