From WikiPilipinas: The Hip 'n Free Philippine Encyclopedia
Sinigang is a Philippine dish consisting of meat or seafood and vegetables simmered in a sour broth, often with a base of rice washing (water used to rinse rice). The sour soup goes well with rice, the staple food of all Filipinos. Because of this, as well as its use of native ingredients, food writer Doreen Fernandez suggested that its origins are most likely indigenous and hence it may be considered the national dish of the Philippines.
Fish, pork, chicken, shrimp, or beef may be used for sinigang. There are usually leafy vegetables: gabi (taro), siling labuyo (red chili), or malunggay leaves, or kangkong (water spinach). Other vegetables cooked in sinigang may include okra, radish, eggplant, tomatoes, sitaw (snake beans), and string beans. The vegetables are chosen to complement the dish's flavor.
 The Flavor
The flavor of sinigang comes mainly from the souring agent used. The souring agent is chosen to complement the meat used in the dish. Sour fruits such as sampalok (tamarind), kamias, sineguelas, and bayabas (guava) are most commonly used to flavor the broth. These days, powdered mixes and bouillon cubes come in some of these flavors and may be used instead for convenience.
Pork sinigang is usually prepared with tamarind, as is shrimp sinigang. Fish sinigang is often prepared using the less sour and slightly sweet guava.
Chicken sinigang, called sinampalukan (from sampalok), is made using tamarind leaves, ginger, onions, and tomatoes. The flavor tends to be spicier than other varieties of sinigang.
 External links
- Kishenblatt-Gimblett, Barbara. "Culture Ingested: On the Indigenization of Philippine Food (Tribute to Doreen G. Fernandez)." 
- More on Sinigang
- Sinigang Recipe