Mix all ingredients of batter to form a dip thick enough to thickly coat back of a spoon. Keep aside.
Heat 2 tablespoons of oil in a frying pan. Add asafoetida, mustard seeds, green chillies and onions. Saute for a couple of minutes till onions are soft and light golden color.
Add ginger paste, garlic paste, turmeric and salt and sauté for a few more minutes; then add the mashed potatoes, mint leaves and sauté for a couple of minutes.
Allow the potato mixture cool down and divide the mixture into 8 portions, shape into round balls and keep aside.
Heat oil in a wok for deep frying
Coat each of the potato balls in the gram flour batter and gradually let it into the oil and deep fry until golden brown in color.
Drain on absorbent paper and serve hot