Soak 200 grams of sabudana (sago pearls) in water for 4-5 hours or overnight. Drain the water and keep the sabudana aside.
Boil and mash 2 medium-sized potatoes. Mix the mashed potatoes with the soaked sabudana.
Add 100 grams of coarsely ground roasted peanuts, 1 finely chopped green chili, 1 teaspoon grated ginger, 1 tablespoon chopped coriander leaves, 1 teaspoon cumin seeds, 1 teaspoon lemon juice, and salt to taste. Mix well to form a dough-like consistency.
Divide the mixture into equal portions and shape them into small, flat, round vadas.
Heat oil in a deep frying pan over medium heat. Once the oil is hot, carefully slide the vadas into the oil and deep-fry them until they turn golden brown and crispy.
Remove the vadas from the oil using a slotted spoon and place them on a paper towel to absorb excess oil.
Serve hot with green chutney or sweet yogurt.