Wash and soak urad dal for 4 hours.
Place half of the soaked dal into the grinding jar and add 2 to 3 tbsp of water. Grind to a smooth batter using very little water. Do not add too much water at once. The batter should be dry and not flowy. Grind until the batter is smooth and fluffy. Remove from the jar and repeat the same with another half of the soaked dal. Remove the batter into a large mixing bowl.
Add chopped green chili, chopped ginger, chopped coriander leaves, chopped curry leaves, and salt to the batter and mix well.
Set the batter aside for 1 hour.
Heat oil in a kadai for deep frying. With wet hands, place a spoonful of batter on your palm and make hole or dent with the thumb and slide the batter into the hot oil carefully.
If you find this step difficult, just take a spoonful of batter and drop into the oil. Only the shape will differ, the taste will remain the same.
Fry vada on medium-low flame for 5 minutes on each side.
Remove vadas and place it on a kitchen tissue.
Serve hot with sambar and chutney.