Wash and soak the Tata I-Shakti whole Green Moong for 4 hours in lots of water.
After 4 hours, drain and grind to a paste with the ginger, chillies, salt and keep aside.
Pressure cook the potatoes. Peel and using a masher or ricer, mash the boiled potatoes well. Keep aside.
In a heavy bottomed pan, heat the mustard oil. Add the sliced onions and red chillies and fry on a medium heat until onions are golden brown. This will take around 8-10 minutes. To this, add the mashed potatoes and salt. Mix well for 2-3 minutes on low heat. Remove into a bowl and keep aside.
To prepare pesarattu, heat a seasoned cast iron or non-stick tava.
Using a kitchen tissue, apply a few drop of oil on the surface. Once the tava is hot, pour 1-2 ladles of batter and move in circles outward to get a thick dosa.
Drizzle a teaspoon of oil along the circumference and allow to cook for 1 minute or so on one side until it turns golden brown and crisp. Turn over, add some oil and allow this side to turn golden too.
Remove onto a plate and place a tablespoon of alu-chokha in the center and fold the pesarattu over and serve hot with chutneys of choice.