Sour fish is a product processed similarly to the various soured meats that are popular in Thailand. The process uses rice as a source of carbohydrate (starch) and then its conversion to sugar and subsequently the metabolism of the sugar to lactic acid. It's the lactic acid which gives the food its sour taste.

The addition of salt to the souring mixture reduces the likelihood of unwanted bacterial contamination thus reducing the chances of a pathogen being introduced and spoiling the meat/fish and possibly causing illness to consumers. This is also the reason why the fish can be left at room temperature for the two days of fermentation without being contaminated.

The enzymes and the cofactors required for the reaction are already in the muscle tissue of the fish or meat. It does need to be fresh though as many of these biochemicals will be destroyed on storage. Ideally the fish is killed at the time of processing. Meat is a little more forgiving and you don't have to sacrifice the beast at your back door.




Ingredients:
  • 1 fish of any kind (tilapia is recommended) scraped and cleaned very well but any Fatty fish is the best.
  • 1 tbsp. sea salt
  • 1 cup  steamed rice
  • 6 cloves garlic (minced)
  • 1 tbsp. rice flour
  • 1 egg (beat)
  • 1/2 cup sliced red onion or minced garlic (fried)
  • 4 kaffir lime leaves (fried)
  • 4 dried chillies (fried)
  • water
  • resealable plastic bag
  • plastic food container
Method:
  1. Mix rice flour with water and clean the fish with it.
  2. Clean inside the mouth and abdominal cavity really well.
  3. Soak steamed rice in the water and drain it.
  4. Put clean fish in a big bowl and sprinkle the salt all over the fish. After that, add minced garlic, steamed rice and mix it altogether.
  5. Tuck the rice into the fish mouth and stomach. Then put the fish in a plastic bag and seal it.
  6. Store the fish in plastic container and seal very well. Leave the fish outside refrigerator at the room temperature for 3 days.
  7. On the forth day, move it into the fridge.
  8. It should be sour about this time. 
  9. Remove all the rice that cover the fish but leave some of it inside the stomach.
  10. The fishy smell will be quite strong but expected.
  11. Dip the fish into a bowl of beaten egg then fry on medium heat while the vegetable oil is hot.
  12. When you serve it, dress the fish with fried onion, fried garlic, fried chili and fried kaffir lime leave. (Squeeze  lemon juice onto the fish if it is not sour enough)
Serve with steamed rice or sticky rice.

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