Wash & clean the fish. Marinate cleaned fish with crushed ginger & garlic, green chillies, curry leaves and salt. Add 1/2 cup water to this and bring it to boil.
Reduce the flame and cook till the fish is done and water is dried. Remove the bones from the fish and mince it with a fork or a wooden spoon.
Heat oil in a pan & and add onion. Cook till it softens, no need to brown.
Add minced fish & stir. Add salt & pepper. Stir well. Add garam masala. Cook for 5 more minutes.
Mash the boiled potatoes. When the fish mix cools, add mashed potatoes and mix well.
Shape the cutlets. Beat the egg white. Dip the shaped cutlets in egg white & roll with bread crumbs.
Heat oil in a deep pan on medium - high. Once the oil is hot enough (not smoking), reduce it to low -medium. Add cutlets and fry till it's golden brown on both sides.