Tacacá is a mouth-numbing Brazilian soup made with large dried shrimps, tucupí (wild cassava byproduct), manioc starch, hot yellow peppers, and jambú – a leafy plant with anesthetic properties. To make tucupí, the juice extracted from a specific variety of sour cassava called mandioca brava (lit. angry cassava) is boiled, then left to ferment to eliminate the high levels of cyanide it possesses in its raw form.
After the fermentation process is over, the resulting sauce is distinguished by a yellowish color and an intensely acidic flavor. The mouth-numbing sensation of the soup comes from the jambú plant, which apart from being used in cooking, has also had a long tradition as a folk remedy in northern Brazil, especially in the states of Pará and Amazonas.
In northern Brazil, the soup is typically sold in the afternoon, usually by female vendors called tacacazeiras. It is traditionally served piping hot in hollowed-out gourds known as cuias, although some vendors offer it in ceramic bowls.