Medhu Vadai is a popular South Indian Snack and also it is served for breakfast with Idli, Sambar and Pongal.
Soak the urad dal for 4 - 5 hours. Drain water completely and grind it to a smooth and fluffy batter (Sprinkle little amount of water while grinding for a fluffy batter).
Add the chopped onion, green chilies, curry leaves, grated ginger, chopped coriander leaves, salt and mix well.
Divide the batter into small portions and make a hole in between and deep fry in hot oil until the color changes into golden brown.