Tsaoko

Tsaoko (Lanxangia tsao-ko, formerly Amomum tsao-ko) is a large herb of the ginger family (Zingiberaceae), 2–3 m tall, forming clumps from a rhizome in moist mountain forest. The leaves are large, lanceolate to spatulate, long-stalked, clearly veined. The inflorescence is a short spike at the base of the stem bearing small pale-yellow flowers. The fruit is an elongated ovoid to nearly round capsule, reddish-brown when fresh, turning greyish-brown when dry, with longitudinal ridges; the thick wall encloses many dark-brown, oily, strongly pungent aromatic seeds. The dried fruit is an essential seasoning of southwestern China and of the Vietnam–China border region.

Tsaoko grows in southwest China (Yunnan, Guizhou, Guangxi) and the northern mountains of Vietnam (Lao Cai, Lai Chau, Son La, Ha Giang), wild under moist forest cover. Fruits are harvested August–December and dried; they are usually toasted before use to release their fragrance. In cooking, roasted cracked tsaoko is the secret of beef pho broth (northern Vietnam and many pho shops) and is used in hotpot, braises, meat dishes and northwestern specialties; it is celebrated as the signature 'pho aroma'. In Chinese medicine tsaoko is pungent and warming, entering the spleen and stomach; it warms the middle, dispels cold, aids digestion and stops vomiting, used for bloating, cold stomach, nausea and cold-damp diarrhoea. Heavy harvesting has placed the species as Near Threatened (NT) on the IUCN Red List; it is now being propagated under forest canopies.