Sinigang na Baboy (Filipino Sour Pork Soup)

Sinigang is an ancient Filipino dish believed to have been influenced by Philippine's neighboring countries. It's similar to that of the sour soup based cuisine of other Asian countries like Indonesia's "Sayur Asam", Vietnam's "Canh Chua" and Malaysia's "Singgang". This dish uses pork as the main ingredient. Beef, prawns, fish, and chicken can also be used to replace pork.
By tradition, the souring ingredient of this dish comes from a tamarind fruit. Guava can also be used and will develop a more mellow, refreshing flavor. Today, a popular powdered sour-soup based ingredient called the "Sinigang Mix" is commonly used. This Sinigang Mix powder is as popular as it is commonly available in most Filipino stores and supermarkets. It comes, popularly, in tamarind and guava flavor.
INGREDIENTS
500 gms pork belly cut into 1cm thick strips
1 pcs medium sized tomato, quartered
10 pcs sitaw (Filipino string beans), cut 2 inches long
1 pc medium sized white onion, quartered
1 pc eggplant, sliced and panfried
1 bundle kangkong Filipino (spinach)
2 pcs. cayenne chili pepper
15 large tamarind pieces or 1 package tamarind base powder
METHOD
Wash pork belly and soak them in cold running water for an hour to remove remaining blood on the pork's flesh.
Meanwhile, wash tamarind and place in a pot with 1 cup water. Bring to a boil and cook until soft and outer skins begin to burst. With a fork, mash tamarinds. In a fine mesh strainer set over a bowl, pour tamarind and liquid. Continue to mash with a fork, returning some of the liquid into the strainer once or twice, to fully extract juice. Discard seeds and skin. Pour tamarind juice into a bowl. Set aside
Submerge pork in a medium pot with a liter of water together with the tamarind juice. If using packaged tamarind base, add into pot and stir until completely dissolved. Bring to a boil without covering the pot to allow the scum to float. Skim off scum that accumulates on the surface.
After the broth clears up, simmer for 60 - 90 minutes or until the pork is tender.
You can add more water at this stage if lots of it had evaporated. Add salt to taste.
Add all the vegetables except kangkong and fried eggplant, bring to rolling boil for about 2 minutes. Add the rest of the vegies and boil for another minute​
Transfer the Sinigang to a serving bowl and serve with white rice.