Ambul Thiyal (Sri Lankan Sour Fish Curry)

500g firm fish steaks cut into chunks
1 tablespoon tamarind paste
1/4 cup vinegar
1 med onion chopped
1 tsp grated fresh ginger
2 cloves finely chopped garlic
1 tsp salt
6-8 curry leaves
1 piece lemon grass or 2-3 strips lemon rind
cinnamon stick
generous shake of spices :fenugreek, pepper, chilli powder
1 1/2 cups water
generous slug of oil

Soak the tamarind in the vineger until soft, mix well so there are no lumps.
Put all ingredients into a pan and mix well. Keep for 45 mins.
Bring to a boil. Reduce heat and simmer uncovered until fish is
cooked and gravy is thick.(DO NOT STIR) Shake pan and turn fish
pieces carefully once or twice during cooking.
Serve with white rice, and other accompaniments such as pol sambol, dahl, poppadoms and chutney.