Som tam
Green papaya salad is a spicy salad made from shredded unripe papaya. It is generally believed to have been created by the Lao people and is considered one of the national dishes of Laos. Green papaya salad is also popular in neighbouring Thailand's Isan region, whose population is mainly composed of ethnic Lao and from where it spread to the rest of Thailand. Green papaya salad has also spread to the rest of the continental Southeast Asia (Cambodia, Myanmar, and Vietnam), as well as Xishuangbanna (China). Papayas and chili peppers were introduced to Southeast Asia by the Spanish and Portuguese explorers in the 17th century from the Americas. Simon de la Loubère (1642-1729), a French diplomat, mentioned in his book that the cultivation of papaya was already widespread in Siam in 1693. Although it is unknown when papayas and chili peppers entered Laos specifically, they had already been fully integrated into the Lao territory by the time Jean-Baptiste Pallegoix and Henri Mouhot visited in mid-1800s, and were listed among key ingredients for preparing main Lao dishes. Tam som was mentioned as a favorite Lao dish by a former Lao politician, Katay Don Sasorith (1904-1959), in a memoir recounting his experience during his primary school years in 1910s. Papaya, among other fruits, were cultivated in Cambodia by Chinese settlers who immigrated in the 1500s from Hainan, China. The Lao name for papaya is mak hung and was likely derived from l'hun or lohung/rohung as papayas are called in Khmer through Khmer Loeu living in provinces bordering the southeastern Laos. Thai historian Sujit Wongthes has speculated that the green papaya salad originated in the communities of ethnic Chinese–Lao settlers living in what is now Central Thailand, who adopted the ancient Lao tradition of preparing salads from fruits, called tam som, to make salads from papayas. The new dish became known as som tam (the reversed order of tam som) during the early Rattanakosin period in late 18th to early 19th centuries and, along with the papayas, then spread to today's Northeast Thailand following the construction of the Northeastern railway line during the turn of the 19th–20th centuries. The dish became more popular after the opening of Mittraphap Road in 1957, and has since become widely adopted by the ethnic Lao people of both Isan and Laos. Likewise, the hot flavour also spread to Isan and Laos from Central Thailand, which had been introduced to chilli peppers first.
Source: Wikipedia