Soak urad daal for 2-3 hours, drain water after that and grind it to smooth paste in the grinder with very less water.Add chopped onion and green chilies. Add salt according to your taste and mix well in one direction only till the batter becomes light. Keep it aside for 1/2 an hour.

Vada: keep a kadhai in stove on medium flame and put oil in it. Now take some water in a bowl and take the batter make small hole into it and put it in oil. Deep fry wada on medium flame till it turns golden brown and crispy and wada is ready.

Take a plate and put Sambhar and vada into it, ready to eat hot.