1) While soaking sabudana pour water more than the level of sabudana in a vessel for about 1″. Some sabudana gets soft after 2 hours, some may take up to 4-5 hours.
2) If dough not combining properly than add one more potato and than make a smooth dough.
3) Fry 4-5 vada at a time. They stick with each other. So do not overcrowd the pan while frying them.
4) You can keep this dough in the fridge in advance too. Whenever needed sabudana vada can be fried easily.