Gaeng som or Kaeng som is a sour and spicy fish curry or soup with vegetables popular in central Thailand.The curry is characteristic for its sour taste, which comes from tamarind (makham). The recipe uses palm sugar to sweeten the curry.
A paste called “nam phrik kaeng som” is prepared as a base for the curry, to which water and the ingredients are added. The preparation of this paste includes shrimp paste and shallots and all the ingredients are pounded with a mortar and pestle. This paste can be made from dry red chilies and one made from fresh red chilies. Some recipes state that large chilies should be used, others prefer bird’s eye chilies.
Fish or shrimp may be used as the basic ingredient. Preferred fish are those that keep their consistency after boiling, such as Channa striata or other equivalent marine fish in coastal locations. One variant uses fish eggs. Kaeng som is usually served with steamed rice.
Traditional vegetables used in household preparation include drumstick pods (marum), green papaya, and Sesbania grandiflora flowers (dok khae), including the red variant of the flower in kaeng som dok khae daeng. Other locally available vegetables are used in the traditional versions such as Ipomoea aquatica (phak bung) and Neptunia oleracea (phak krachet).