If there is any water, which most likely there should not be, drain in a colander.Rinse sabudana well until water turns clear. Soak it in ½ cup water overnight. In the morning, the sabudana would have absorbed all water. Press one sabudana ball between your fingers, and it should crush easily.
Grate boiled potatoes in a large bowl. Transfer the saubdana to the bowl. Add crushed roasted peanuts, cilantro, green chilies and salt. You may also add ginger or lime juice if you like.
Divide the mixture into 13-15 equal parts, make round balls and then flatten them a bit.
Heat oil on medium-high heat in a kadai or wok. Make sure the oil is hot by dropping a single sabudana ball. It should quickly float to the top.
Now add 3-5 vadas to the oil depending on the size of the kadhai, don't overcrowd the kadai. Fry vadas until golden brown and crisp from both sides. Transfer to a plate covered with paper towel to drain any excess oil.
Spray some oil in the air fryer basket. Place vada's in a single layer leaving space between each. Brush or spray some oil on top of the Vada's.
Air fry for about 16-18 minutes at 390°F. Flip the vada's at about the 10 minute mark.