Clean and cut the fish in to small cube like pieces(use thick fleshy pieces with out skin and bones if possible),wash well and drain water.
marinate the cleaned fish pieces with chili powder, turmeric powder,salt and vinegar,cover and keep aside.
peel the skin of garlic and ginger wash and slice.cut green chili in to medium pieces.
heat gingelly oil in a deep frying pan(I used 100 ml ) and deep fry the fish pieces till crispy.remove from oil and keep aside.
in the same oil (you can use fresh oil if you want.fried oil is unhealthy but taste wise good) add garlic, saute well until it become soft.
then add ginger,green chili and curry leaves, saute well till every thing become golden brown.
now reduce the flame and add chili powder saute till raw smell goes.
now add vinegar and warm water let it boil,then add fried fish and cook for few more minutes.add fenugreek powder. mix well and switch off the stove.check salt consistency,add more if required.
let it cool ,then transfer to an air tight container.keep aside for one week(it will take time for the flavor to settle in)then serve with steamed rice