Wash the fish and pat dry.Now marinate fish with salt, 1/2 tsp turmeric,1/2 tsp black pepper powder and 1 tsp gondhoraj lemon juice. Set aside for 10 minutes.In a mixer grinder,blitz chopped onion, ginger garlic paste and green chillies to a smooth paste. Set aside.Add cashewnuts and yogurt in the mixer grinder and blend to a smooth paste.Set aside.

Heat oil in a wok or deep frying pan and shallow fry the fish.Remove with a slotted spoon and set aside.In the remaining oil add cumin seeds and half crushed whole garam masalas and black peppercorns.When they splutter, add the onion, ginger, garlic and green chillies paste.Keep stirring over medium heat till the paste changes colour.Now add turmeric,Kashmiri Red Chilli Powder, cumin powder and black pepper powder. Add salt and sugar to taste and fry till oil leaves sides.

Lower the heat and add the blended yogurt cashewnut paste.Keep stirring and add 1 cup water. Mix and cook over high heat until the curry starts boiling. Add the fried fish pieces and cook till the gravy is lightly thick.Remove from heat.Gently stir and garnish with few gondhoraj leaves,lemon zest and sprinkle 1 tbsp gondhoraj lemon juice.Add some slit green chillies.Close lid and let the flavours of gondhoraj lemon infuse in the curry for 2 minutes.