Wash the urad dal and soak it for about 3 to 4 hrs.
Drain the water and grind it along with the green chilli. As I used serrano chilli, I went with one. Please adjust the number of chillies as per your taste preference.
Grind it by just drizzling water, not more than 1/2 cup of water. I grinded it using my wet grinder.
Checking the Batter Consistency
Take a bowl of water or glass of water.
Take a small amount from the batter and drop it the glass of water.
It should not spread out or dissolve and mix with water. It should maintain its shape and should float on top like below. That’s the right consistency.
Adding Other Ingredients
Keep this ground batter in the fridge for half an hour.
Now take the batter out and add the chopped cilantro, onions and salt. Salt should be added just before frying. Salt has the tendency of ooze out water and it will make the batter watery.
Mix this well and let it sit till the oil gets heated.
Shaping the Vadai and Frying
Heat the oil required for frying in wide kadai. Once the oil is hot bring it to medium and let it stay in medium heat for few minutes. Frying in hot oil, might brown the vadai and also inside might not be cooked well. For soft and crispier vadai, frying it in medium heat is the best.
While the oil is getting hot, keep the batter and wide bowl with water.
Wet your palm and shake off the excess water. Take a lemon sized batter and slowly toss it in your palm to make a ball.
Now bring this ball to the top of your palm and keep your thumb finger free. Basically the batter should be in your forefinger, middle finger, ring finger and pinky. Now with the thumb finger make a nice big hole in the center and slowly drop in the oil.
After 30 seconds flip the vadai and let it cook on the other side.
Deep fry until it turns light golden brown and by that time the oil bubble sound will also cease.
Repeat this process for the remaining vadai. In one batch I fried 3 vadas.