Heat oil in a saucepan. Splutter the mustard and cumin seeds.

Crush the ginger, garlic and green chillies in a mortar. Add to the oil and saute briefly.

Add the hing and curry leaves and saute.

Add in the mashed potatoes and salt. Toss to combine well. Switch off. Mix in the coriander leaves.

Divide the mixture into 10 balls.

Whisk together the ingredients for the coating and add water to make a thick mixture.

Heat oil in a frying pan till smoking hot. When you drop in a little of the batter, it will sizzle up.

Drop in one ball into the batter, coat all around. Drop into the hot oil. Fry in small batches till browned.

Drain onto a kitchen towel. Repeat till all completed.

Serve hot with green chutney and tamarind chutney, or with ketchup.