Finely chop onion, ginger, garlic and green chili.
Wash the potatoes (not shown in pictures), cook with some salt (wouldn't take much time if you are using a pressure cooker), peel, and finely mash without any lumps.
Clean the fish, place them in a pan (if you are using whole fish, remove the head), add a cup of water, 1/4 teaspoon turmeric powder, and salt. Cook on a medium flame with the lid closed for about 10 minutes. Drain the water, remove the bones, and separate the flesh into flakes using a fork. Ensure that no small bones are left behind. I used mackerels. They have a nice texture and flavour, and is ideal for cutlets (croquettes). You can use any fish or meat of your choice. If you want to save on the preparation time, use canned fish flakes (e.g. tuna flakes).
Heat some oil in a pan. Fry the ginger and garlic on a medium flame for 2-3 minutes.
Add the chopped onions and cook till they are tender. Add green chili, chili powder, and turmeric powder, and continue frying for a few more minutes while stirring.
Take all the ingredients in a bowl - the mashed potato, fish flakes, and the fried onions. Mashed potato should be double the amount of the prepped fish.
Combine the ingredients well. Check for salt, and add more if required.
Divide the mixture into 6 equal portions. Use you hand/s and roll out each portion into a smooth ball.
Gently flatten all the balls into a disc shape with the palm your hand.
Beat one egg in a bowl. Take the breadcrumbs in another one.
Heat oil in a thick-bottomed pan or a skillet.
When the oil is hot, take the cutlet discs, one at a time, roll in the breadcrumbs, dip in the beaten egg, then in the breadcrumbs again.
Reduce the flame, place the coated cutlet in the pan, and fry on a medium flame.
When the breadcrumb coating turns golden brown, and looks crispy, turn them over and fry the other side.
I used less oil and shallow-fried the cutlets. You can add more oil and deep fry them. Take care not to burn them. I fried them in batches, three at a time. The fish cutlets are delicate, and you need to be careful not to break them while handling them.
Once both sides are evenly fried, remove the cutlets from the pan using a slotted spoon, and drain on a paper towel. Serve hot (and serve fresh) with some ketchup to go with it.