Take a wok, heat it, pour enough water, add 1 tsp of regular table salt, mix it, and put 5 pieces (500 gm) of Bhetki fish in it. Turn them after a minute or two and then cover the wok to cook the pieces nicely for about a minute or so.
While it cooks, take 4 slices of bread, and cut their edges. Then cut them into small cubical pieces and keep them aside.
Now, turn off the flame of your gas stove, remove the lid, take the pieces of fish out, and remove their skin. Also, debone them and keep them in a bowl.
Now, to the bowl, add 1 tsp of ginger garlic paste, 1 small piece of onion (grated nicely), ½ tsp of fresh green chili paste.
Follow it with 2 tsp of fresh lemon juice and ½ tsp of salt. (Pro tip: Be careful about the salt as you have added it while boiling the fish before. The amount of green chili paste may vary depending on how spicy and hot you want your cutlet to be).
Then add ½ cup of finely chopped fresh coriander leaves and 1 egg yolk.
Finally, add the cubical pieces of bread you have cut before and kept aside. Mix everything nicely and make a paste.
Now, take about 1.5 tbsp of this mixture or paste and press it with both your hands to give it the flat round, or oval shape of a cutlet. (Pro tip: Be gentle while pressing because it is very soft).
Now, coat it with bread crumbs on both sides. Then dip it in eggwash, put another layer of bread crumbs, and keep it aside. Repeat this process for all the cutlet pieces. (Pro tip: Press the cutlet pieces gently so that the bread crumbs stick to the surface nicely and do not come off while frying them).
Now, give every piece of cutlet the final shape you want in it by using your hand and a knife. Keep them all aside on a plate.
Now take a deep-bottom wok or frying pan and add enough cooking oil to shallow fry the pieces of cutlet and heat it on a high flame on your gas stove. Add the pieces one by one carefully. Do not add too many pieces at once. (Pro tip: The amount of oil needed will depend on the size of the pan and the number of pieces to fry. Also, be careful while adding the cutlet pieces. Add gently not to splash the hot oil).
Fry for about a minute or two in a medium to high flame. Turn them carefully to fry them evenly on both sides. Take them out when they turn to a nice golden-brown color. Repeat the process if you cannot accommodate all the pieces at once. (Pro tip: You may put them on tissue paper to drain the excess oil for health reasons).
Your homemade fish cutlet is ready. Garnish the cutlets with a little bit of salad and serve them hot. You may serve tomato or mustard sauce alongside them.