Soak sabudana in enough water for minimum 5-6 hours or overnight.
Next morning drain all the extra water and spread the soaked sabudana on a kitchen towel for about an hour to remove all the moisture from it.
Dry roast the peanuts in a pan or microwave them .
Let the peanuts cool down completely then coarsely grind in the mixer jar,don't make a fine powder else it become sticky .
Peel the boiled potatoes and grate or mash them .
Take a big bowl and add the soaked sabudana , mashed potatoes, crushed peanuts, green chili, ginger, salt, sugar, coriander, Rajgiri atta , cumin and lemon juice.
Mix everything properly using a spoon or with your hands.
Now grease your hands with little oil and take some portions of the sabudana mixture and make small or medium size patties.
You can make a hole in the center like we make in medu vadas but its optional.
Heat enough oil to deep fry in a heavy and deep pan.
When oil become hot then gently slide few vadas in hot oil, don't crowd the pan.
Deep Fry on medium heat , turn the side 2-3 times while frying till they become golden in colour from both the sides.
Drain on a paper napkin when done.