Wash the Urad Dal till water runs clear. Soak overnight in 4-5 cups of water – overnight would be perfect.
Next day drain the dal and add the dal about quarter cup at a time. Avoid adding water while grinding, but if the mixer/ grinder jams, add as little water as possible. Remember to wipe off and mix back the dal that sticks to the walls. Stop once you get a smooth thick batter.Take out the batter into a container.
Now add the onion,coriander,green chilies,chopped ginger,salt,baking powder in the dal batter.Now add semolina and you have to whisk the batter to aerate it.Then fill a small bowl with water and drop a pinch of batter in the same. If the batter is right, it will float on top of the water and if not you have to whisk it some more and when done keep aside.
Heat oil in a kadhai for deep frying the vadas. Check the oil drop some of the batter and if it quickly rises to top with slight bubbles its ready.
Now time to fry,wet your hand/spoon, take a small dollop of the batter and gently slide it in the hot oil.Just make sure that they are not too big. Don’t fry more than 4-5 at a time.Turn them around a couple of times so that they are evenly golden on all sides. Once done, take them out with a slotted spoon and drain on a kitchen towel. Serve hot or warm with any chutney of your choice.