Heat oil in a large pan and add the onion and salt. Saute until the onion is slightly wilted.
Add red chilli powder, dry mango powder and chopped ginger. Mix well and sauté for a minute and turn off the flame.
Add the chopped coriander leaves and coarsely ground flattened rice to the onion mixture. Mix well and leave the mixture to cool down.
Mix all-purpose flour with sufficient water to make thick paste.
Cut the spring roll sheets into rectangles and fold it in the form of a triangle and fill with a small portion of onion mixture.
Use the all-purpose flour paste to close the edges.
Heat oil in a pan for deep frying and fry the samosa in batches till golden brown. Drain the excess oil in paper napkin.
Enjoy hot samosa with tomato sauce or green chutney.