Rinse sabudana under water until water turns clear (This is important to get rid of all the starch)

Transfer the rinsed sabudana to a large bowl and add 1 cup water to it. Keep this aside for 4-5 hours(do this overnight).

 In a bowl add sabudana (soaked), potato, corn flour, ginger, green chillies, coriander leaves, red chilli powder, cumin powder and salt. Mix well.

Heat oil in a kadhai. Apply little water in hands and form 4-5 round shape balls from above mix.

 

Flatten each ball and place 1 tsp mayonnaise the middle. Seal and shape it up like a vada.

Shallow fry the vadas until golden brown and crisp from both sides. Serve hot.