- More moisture in the vada mixture, it has more chances to break while frying. You have used soggy boiled potatoes or you have not drained the sabudana well.  - The oil temperature is not right. If the oil is not hot enough then vada will absorb more oil and can break in the oil. So oil has to be moderately hot (on medium heat). - You are moving, disturbing the vada too quickly. Once you add the sabudana vada into the hot oil, do not disturb them for a minute. During this time, the outside layer gets fried and gets enough bind. Then you can flip and move around without fear of breaking. If you have touched them earlier or too soon then it will break in the oil while frying and it becomes a big mess.