Fish curry

Nani`s  way 
Ingredients:
Fish  - 750 gms ,
Mustard seeds  - 4 tsp ( soaked in water overnight ),
Onion -1 ( medium size chopped and grinded ),
Ginger garlic paste - 1 tsp ,
Red chilli pwd - 1tsp,
Black pepper pwd - 1/4 tsp ,
Coriander pwd -2 tsp ,
Cumin pwd - 1tsp ,
Turmeric pwd - 1/4 tsp,
Mustard seeds - 1/2 tsp,
Fenugreek seeds -1/4 tsp ,
Tomato - 2 ( chopped and pureed ),
Green chilli -2  slit ( optional ) 
Oil - 2 tbsp.
Salt to taste .
Water - 300 ml
green coriander leaves .

Ingredients for marination of fish :
Half lemon juice ,
red chilli pwd - 1/2tsp,
Turmeric pwd - 1/2 tsp ,
Salt to taste .
Method :
Wash and pat dry the fish .Marinate the fish and keep in the fridge for an hour .
Make the paste for the gravy while the fish is marinating .
Grind the onion in the blender with little water and keep in a bowl.
Chop the tomatoes and run in a blender and keep aside .
Grind the soaked mustard seeds with ,coriander pwd ,cumin pwd ,red chilli pwd ,turmeric pwd 
,pepper pwd and  the soaked water .Grind to a smooth paste .

Heat 1 tbsp of oil in a non stick pan and lightly fry the fish  pieces .Take out and keep on a plate .
Add one tbsp of oil and add the mustard and fenugreek seeds .

As the seeds crackle and the grinded onions .
Saute the onion till the water evaporates and then add ginger garlic paste and mustard coriander paste .

Fry the masala in medium heat covering slightly as the paste will splutter out while cooking . 

As the water dries out you can remove the cover and fry till the sides leave oil .It will take only few minutes  . Dont fry the masala too much as it will turn bitter as there is mustard paste in it . Add the tomatoes and green chilli .

Let the tomatoes cook for  a  minute and then add a glass of water or 300 ml of water .
Add salt and let the gravy come to a boil .
Stir and as the gravy come to boil add the fish pieces .
 Lower the heat and cover for 5 minute .
Close gas and let it stay in the pan for few minutes .
Fish curry is ready .
Taste salt .

Sprinkle coriander leaves when you serve .
Enjoy with rai pulao or plain hot rice .