Take a cup of sambhar & add 3-4 cups of water bring it to boil (add enough salt). Soak the vadas in it for 1 minute.(this makes the sambhar vada more soft)
Now transfer the vadas into the hot sambhar & keep the sambhar on low flame for 10 minutes.
Now switch off the flame & leave the vada in the sambhar, atleast for another 30 minutes.
While serving, sprinkle some onions & coriander leaves.
Grind it by adding very little water now & then, till it becomes fluffy & soft.
Now mix all other ingredients & deep fry it on medium flame, till it becomes golden brown in color.
Tips for the recipe - The taste & softness of the vada depends upon how fluffy & soft the batter is. It should be super soft and fluffy. Take a pinch of dough and drop it in a cup of water, then it should float. If you are making big vadas as in the photograph then make hole in the center for the vada to cook evenly. If you are making very small vadas then the hole is not necessary. Wet your hands while shaping vadas. This makes the work easy and gives better shape for vadas.