For the Vada fillingPound the green chillies, ginger and garlic using a mortar and pestle.
Heat the oil and add the mustard seeds. When they crackle, add the curry leaves and sauté for a few seconds.
Add the pounded mixture and sauté again for a few seconds.
Add the potatoes, turmeric powder and salt and mix well.
Remove from the fire and cool.
Divide into 8 equal portions. Shape into rounds.
For the outer coveringCombine all the ingredients in a bowl and make a batter using approximately 1/3 cup of water.
Dip each round of the vada filling into the batter and allow it to coat the mixture well .
Deep fry in hot oil, till golden brown. Drain on absorbent paper and keep aside.
ServingSlice each pav into half and spread some dry garlic chutneyinside.
Place one vada in each pav and serve immediately.