Printing may not work inside Facebook. Open this page in Safari or Chrome using Facebook’s browser menu, then tap Print again.

Soaking the vada in fresh water is necessary to get perfect dahi vada. If you want them to be more good in taste you may add half cup of milk to half cup of fresh water. Add half tsp of sugar and then soak vada. They would taste better.
I have used greek yogurt as it taste best than any other curd. However, if you don't get it, you may use normal ones or better is homemade. But you have to whisk it first and chill it in refrigerator.
Consistency of batter is also an important factor in getting perfect dahi vada. If batter is wet, you will not able to shape them. If battter is too thick vada would not puff up while frying them. So keep an eye over the consistency of batter.