Ambul Thiyal (Sri Lankan Sour Curry of Fish)

I've posted this after a request from another member, I've never tried it as we don't eat fish but its copied from "The Complete Asian Cookbook" by a fantastic cook Charmaine Solomon. She states that in Sri Lanka the acid used for this dish is called "goraka" but she has used tamarind as its easily available.

• Ready In: 50 mins
• Serves: 6

Ingredients

• 500  g  fish fillets or 500  g  steaks
• 1  tablespoon tamarind pulp
• 1⁄4 cup vinegar
• 1  medium onion, finely chopped
• 3  garlic cloves, finely chopped
• 1  teaspoon  grated gingerroot
• 1  teaspoon salt
• 6 -8  curry leaves
• 1  stalk lemongrass (or 2 strips lemon rind)
• 1  inch cinnamon stick
• 1⁄4 teaspoon fenugreek seeds
• 1⁄4 teaspoon ground black pepper
• 1⁄4 teaspoon chili powder
• 1 1⁄2 cups water
• 2  tablespoons  oil

Directions

1. Wash and dry fish, cut into serving pieces.
2. Soak tamarind in vinegar until its soft. (If tamarind is very dry, heat in an enamel saucepan for a few minutes adding some of the water).
3. When cool enough to handle, squeeze the tamarind in the liquid to dissolve the pulp, strain through a fine nylon sieve and discard seeds and fibres.
4. Put all ingredients into a pan (preferably an enamel or stainless steel pan) and bring to the boil.
5. Reduce heat and simmer uncovered until fish is cooked and gravy is thick.
6. Shake pan or turn fish pieces carefully once or twice during cooking.
7. Serve with white rice.