Marinate 600 grams of King fish with 2 tsp of lemon juice and 1 tsp of salt. Cover and keep it aside for about 10 minutes.
In a plate, take a fistful of coriander leaves with stems along with 20 pieces of mint leaves (pudina), 8 pieces of regular, whole green chilies, 2 pieces of long green chilies (cut into small pieces), a piece of ginger (1 inch size, cut roughly into small pieces), about 20 whole garlic cloves (peeled). Transfer them to a mixie jar and add 1 tsp of cumin seeds, 4 tsp of lemon juice and 1 tsp water. Make a fine paste.
Transfer it to a plate and add ¼ tsp of turmeric powder, ½ tsp of garam masala powder, 1 tsp of dry mango powder (amchur), ½ tsp of white pepper powder, and 1 tsp of coriander seeds powder to it. Follow it up with 4 tbsp of rice flour and ½ tsp of salt. Mix them all very nicely.
Finally, add 2 tsp of water to it. Mix again and make a relatively thick masala paste.
Coat all the marinated fish pieces nicely with the masala paste one by one on both sides. Cover and keep it in the fridge for 10 minutes.
Heat 4 tbsp of cooking oil in a frying pan over a medium flame. Put the coated fish pieces carefully in it one by one. Let it fry on one side nicely for 6 to 7 minutes on a medium to low flame, applying hot oil on its surface with the ladle carefully. Flip the fish pieces carefully and cook it again for 6 to 7 minutes more.
Then, flip them a couple of times. Finally, fry them on a high flame for about 30 seconds. Remove them one by one to a plate when done.
Garnish them with finely chopped fresh coriander leaves as required and squeeze some lemon juice. Your tasty and spicy homemade green masala fish fry is now ready to enjoy. Serve with green chutney, sliced onions, tomato rings, and lemon wedges.