Soak Urad dal and rice together for 2 to 3 hours. Now drain it and grind in a blender to a very smooth paste.
Add little water as needed to make a smooth paste. Tranfer this to a mixing bowl and set aside.
Now add onions, green chilli, ginger, curry leaves in this and mix well.
Take a small portion out of this and flatten it with your hands. Make a small hole in the center and drop in hot oil.
Fry this till golden brown and drain in a paper towel.
Serve with chutney and sambar.
1) Add little water while grinding. If you add lots of water, you wont be able to shape the vadai and the vadai will drink lots of oil.
2) Don’t keep the batter out for more than 3 hours, as it will turn sour and ferment. The vadai wont taste good.
3)If your batter is not thick enough, add little all purpose flour / maida to it and mix it up. Dont add too much of it.