Clean the fish(I used Tuna for this pickle) with out skin and bones.
Add 2tsp of salt and turmeric powder to the fishand leave for 1 hourThen drain the water inside and frythe pieces .Donot overfry.
Grind cleaned garlic and ginger along with greenchilli and curry leaves. Grind mustard coarsely.On a thick bottomed pan add oil and fry mustard powder,and ground paste till golden brown.
Then add the chilli powder, fennugreek powder, asafoetida powder, Turmeric powder and stirr for 1 minute and add vinegar and left oil along with salt.when it is about to boil switch off the stove.
Store in a dry container .It will stay for months if use in proper way.(Use only dry spoons. Always keep the container air tight.)
Enjoy delicious fish pickle.