Steam or pressure cook potatoes and mash coarsely when warm.Heat oil in a nonstick pan.Sprinkle mustard seeds and when it crackles,add chopped ginger and garlic and fry lightly.Add few curry leaves and fry.Then add the mashed potato,salt to taste,turmeric and red chilli powder.Add chopped green chillies and coriander leaves and toss till all masalas are mixed in potato.Make balls out of potatoes.Then flatten with palm.
Make a thick batter out of gramflour,rice flour,salt,red chilli powder and little turmeric.Add 1 tbsp warm oil and baking soda while making batter.Heat oil.Dip each flattened ball in batter and fry each vada tossing when one side is done till golden brown.Take out all vadas from oil when done and spread on a kitchen tissue to remove excess oil.Serve hot with ketchup or green chutney.
For chutney :Assemble all ingredients and grind to a smooth paste using minimum water.Mix lemon juice and salt to taste.
