Wash sago in running water for 3-4 times. Soak in 2 ½ cup of water for 5-6 hrs.
After 5 hours,drain water completely from Sabudana and keep it in a colander bowl,so that water drains away completely,if any.
Boil Potatoes,in a pressure cooker for 2-3 whistles.
Peel potato skin and mash the potatoes completely.
Dry roast peanuts on an iron skillet ,till skin starts peeling.Allow to cool completely.
Take peanuts in a mixer jar ,coarse powder it using pulse mode for 10 seconds.
In a mixing bowl,add sabudana ,potato,cumin seeds,salt,grated ginger,green chillies, coriander leaves,lemon juice,1 teaspoon of oil and mix everything very well.
Take small portion of mixture ,make it round using hands and press it lightly to form a shape of flat round vada or patties.
Preheat the oven to 220 deg celsius.
Grease the baking tray with oil ,and place the vada and brush the top of vad with oil.
Once preheated , Bake it for 20 minutes. In between, around 15 minutes flip the vada to other side and again continue baking.
Now Place the oven in grill mode and grill it for about 4-5 minutes till the top turns nice golden in colour.