Wash and soak the urad dal overnight and grind to a fine paste by adding very little water. The batter should be thick enough to make the vada. Beat the batter very well till light and fluffy. Add salt, baking powder and beat well again.

To taste whether the batter is ready or not, slowly drop the batter in a glass of water. If the batter floats on the top, it is ready, if not you need to beat it more. Pre-heat oil in a deep frying pan, place a plastic sheet in your palm. Wet the plastic sheet and place a little batter and shape like a big lemon sized ball.

Flatten the top of the ball with wet fingers and drop slowly into the hot oil. Deep fry on medium heat for sometime and then fry on low heat till golden brown. Remove these deep-fried vadas into a bowl of water and let them soak for 15-20 minutes. Remove and gently press between your palms so that excess water oozes out. Keep them aside. Finish making vadas with the rest of the remaining batter and put them in water like you did for the earlier batch.

Pass the yoghurt through a sieve to ensure that there are no lumps. Add in the sugar, salt and mix well. To make the Dahi vada Masala: Dry roast the cumin seeds till light brown and fragrant. Grind to a smooth powder. Finely chop the green chilies and coriander leaves. Scrap the ginger clean, wash and cut into julienne. To serve, place the vadas in a serving bowl and pour the curd mixture evenly all over the vadas and cover them completely. Sprinkle chat masala powder, red chilli powder