The literal translation of Sayur Asem, is Sour Vegetables. It is a spicy sour soup and is a common household dish originating from Java. There are two versions; The Central Java and the West Java. The Central Java version is the one in the picture which is a little more time consuming to make - the broth is made from beef stock and the spices are grind in a mortar with peanuts that give the soup a slightly murky look but rounded flavor. The West Java version is a vegetable based broth with the same spices but without grinding the peanuts and therefore the broth is clearer. The sourness comes from "Pohon Belimbing Wuluh" or in English; Cucumber or Sorrel Tree - an image the fruit is dipicted in the picture. Not many traditional markets sell these fruit and if that is the case, it can be replaced with Tamarind soaked in a little warm water. Belimbing Wuluh is used in many traditional Javanese dishes. In Aceh, the fruit is sundried (known as Asam Sunti) and then used in some of their traditional cuisine.
The vegetables used are corn, yard long bean, chayotes (pear squash) and young jackfruit. Belinjo leaves and fruit is also a key ingredient in this dish, I don't know what the English word is but the latin name is; Gnetum Gnemon. The leaves are hard in texture, so it should be preboiled before adding to the broth. The fruit that grows on this tree, is a nut actually and is thrown in whole in the broth. The flavor of the fruit is slightly bitter and nutty and is the prime ingredient to make "Emping" chips. The process to make these chips is not only time consuming but labor intensif. First you have to peel both layers of the fruit before you get to the nut, then you have to grind it into a fine paste, then roll and shape it flat to the size of a large coin. Afterwards you sun dry it until it's hardened and crisp and then fry it. It's so much easier to just buy these chips raw and fry yourself or ready to eat.
The spices used to make this soup are; Shallots, garlic, candlenut or peanuts, shrimp paste and chilli, all this is ground to a fine paste and sauteed with bay leafs and galangal root for a few minutes before putting into the broth. Let the broth simmer for awhile before adding whole skinned peanuts, the belimbing fruit or tamarind, season with a salt and grated coconut palm sugar. The sugar will balance out the sourness of the soup. Who said it was easy...but a favorite among many of my family members.