To begin with, pressure-cook the bananas with their peel on. Cook them for about 2 whistles or 10 mins. Do not rush through this process as we want the bananas to be soft and tender to make a smooth mash.
Remove from water and allow them to cool. When comfortable to touch, peel the banana. Transfer it to a big bowl.
Mash banana with a fork or potato masher.
Now add Sattu, garam masala powder, chopped onion, green chillies, coriander and salt (rock salt). Mix well.