Cutlets are one of the dishes that I used to prepare during my initial stages of cooking. It is easy to make and tastes great. But I have to agree to the fact that it takes a bit of time to cook. Again, plus point is that these patties can be frozen without frying and can be fried when ever you feel like treating yourself. For freezing the patties, shape them and place them in a container in layers, one layer of cutlets over another layer of cutlets, and baking paper or wax paper in between so that they don’t stick to each other. i.e, one layer of uncooked cutlets, a sheet of baking paper and another layer of cutlets on top of baking paper. You can take a few out s required, thaw them and fry them as per need and it would taste as fresh as new. No one would even know that they were frozen once. These are usually served along with evening tea, or during Iftar or to serve any guests. My mom always tricks my sisters into eating these fish cutlets as they don't eat fish and these almost tastes like chicken cutlets and fish taste is not very obvious.
Here, I have used only egg whites as the yolks make the oil frothy while frying the patties. 
Ingredients:
2 Canned tuna in spring water
1 large potato, 250g
500g onions, chopped (3 ½ medium size, 3 ½ cup chopped)
1 Tablespoon pureed Garlic
1 Tablespoon pureed Ginger
3 medium hot Green Chillies, cut into thin rounds
½ cup chopped Coriander Leaves
A pinch of Turmeric powder
1 teaspoon coriander powder
½ teaspoon Garam Masala Powder
2 teaspoon Kashmiri Chilli Powder
2 Tablespoon Lime Juice
Oil – as required to fry the cutlets
4 egg whites
Breadcrumbs – as required
Update: I have forgotten to add potato in the ingredients, which is now added.
Preparations:
1. In a large non stick frying pan or a wide saucepan heat 2-3 tablespoons of oil.
2. Add chopped onion and salt and sauté until onion becomes soft and translucent.
3. Add chopped chillies along with pureed ginger and garlic. Sauté for 2-3 minutes or until the raw smell goes off.
4. Add all the spices and coriander leaves. Cook for couple of minutes.
5. Add drained tuna; stir well breaking all the lumps.
6. Add lemon juice and adjust seasoning if necessary. Cook on low - medium heat for about 5-10 minutes until the flavours are well blended.
7. Meanwhile Cut the potato into 4 large chunks and cook it in salted water just until soft. Make sure the potatoes don’t go really soft and fall apart. They have to be firm, but cooked through. If it goes really soft, cutlets will fall apart while frying.
8. Drain water completely and peel potatoes. Mash them with fork lightly with little lumpy texture; whilst hot/warm. (Don’t make it into a paste or a smooth puree).
9. Add mashed potatoes to the fish masala prepared earlier and mix well.
10. Make lemon size balls out of this mixture, flatten it into 1” thick patties; dip it in lightly beaten egg whites and roll it in breadcrumbs. Tap off extra crumbs and leave it aside for 5 minutes to dry a bit.
11. Heat a frying pan (any size) and add vegetable oil to a height of 1-2 centimetres. Fry the patties on medium heat until they turn golden brown colour, flipping them over a couple of times to ensure even browning.
12. Serve hot or warm with ketchup.