To prepare the Sabudana Vada, soak the tapioca pearls (sabudana), in 1 cup of water for about 4 - 5 hours or overnight.
Next day, transfer the soaked sago into a metal colander to drain all excess water.
To prepare the mixture for the vada, in a large mixing bowl combine boiled potato, soaked sabudana, ginger, chili, peanuts, coriander, salt, and spices.
Mix thoroughly while mashing the mixture with your finger to form a smooth non-sticky dough-like mixture for the vada.
Heat oil for deep frying in a pan over medium flame.
While the oil is heating, divide the mixture into small sized balls. Next, flatten the balls to half inch or so thickness gently using fingers.
Shallow fry or deep-fry the vada in small batches in hot oil till golden brown and crisp from both the sides.
Drain Sabudana Vada on an oil absorbent paper.
Serve Sabudana Vada with green chutney and a cup of tea.