Both Eileen and Nil wanted to know how I make my mackerel curry, so I am posting my "recipe". I really don't use precise amounts of ingredients, but I tried to estimate how much of what I put in, because my daughter used to hate it when she'd ask me how to cook something and I'd say, "some onions, some tomatoes, some curry powder", etc. (But now that she's been cooking for herself for over 5 years, she cooks the same way I do - some of this and some of that! LOL.)
I use canned (tinned) mackerel packed in either water or brine. I can find mackerel in water at the grocery store; the ones I buy at the dollar store tend to be packed in brine. If I buy the ones in brine, I don't add any additional salt to the dish. I don't discard the liquid the fish is in; I use that for my gravy. But, you may discard it, if you prefer, and use fresh water and milk to make the gravy, or, only the milk (either coconut milk or regular milk).
1 can mackerel, packed in water or brine
1 small onion or half a larger onion, sliced (you can add more if you really like onions)
1 tomato, chopped or sliced (again, add more if you like lots of tomato)
1 green chili, sliced (remove seeds or omit if you don't want it too spicy)
2-3 cloves of garlic, sliced
1 small piece of ginger
1 sprig (several leaves) of curry leaves (can substitute a bay leaf if needed)
1 piece pandan leaf (optional, don't worry if you don't have it)
1-2 heaped teaspoons of curry powder (I use a mixture of dark roasted and yellow curry powder; my daughter tends to use turmeric instead of yellow curry powder)
1 tsp chili powder (adjust to how spicy you want the curry; can add less chili powder and add paprika for color, if you like); yes, I add both chili powder and green chilies to my curries
1-2 whole cloves
1-2 whole pods of cardamom
1/2 - 1 can coconut milk (can substitute regular milk, if needed)
1-2 table spoons of oil
1/2 lemon (or a lime)
Salt to taste (if needed)
Saute the onions and tomato in the oil, add the green chili, garlic and ginger, curry leaves and pandan leaf and saute for about a minute. Add the liquid from the can (or water) and the coconut milk (or regular milk), add the curry powder, chili powder, cloves and cardamom, and bring to a boil; reduce the heat and let the gravy simmer for about 5 minutes. I add the fish at the very end, and simmer only until the fish is warmed through, since it is already cooked. That way, the fish stays whole (unless you wish to break it apart). The final step is to add lemon juice. I add lemon because I have lemons growing in my garden; one can add lime juice, if preferred.
Now, the short-cut method, which I've been known to use, occasionally, is to skip the sauteing of the onions and tomatoes, etc., just dump the liquid from the can into a saucepan, add all the ingredients other than the fish and lemon juice, bring the gravy to a boil, add the fish and lemon juice! That's what I did the other night! My daughter was shocked when I told her I did that, because she does the sauteing, etc., the way I told her to do. I've even been known to omit the garlic and ginger, on occasion (often when I don't have these ingredients on hand). It still makes a very good curry, in my opinion.
I hope you make this curry and enjoy it.