A Szechuan pepper is not really a pepper at all — it is a rust-colored dried berry from the Chinese prickly-ash tree. This small citrus tree is native to the Sichuan province of southwestern China; the berry, also known as a Sichuan pepper, gets its name from this region. Although Sichuan cuisine is often hot and spicy, the Szechuan pepper itself is generally milder; it has a unique citrus flavor and may leave a tingly, numbing sensation in the mouth. Szechuan peppers are frequently used in the cuisines of China, Japan, Nepal, Tibet and Bhutan.
The Szechuan pepper spice is made by roasting and grinding the dried berry shells; the gritty black seeds are usually discarded along with any stems and thorns. The Japanese also dry and grind the leaves into a powder called sansho, which is often used to flavor soups and noodle dishes. The whole, fresh leaves, known as kinome, can add a mint-lime flavor to bamboo shoots and other vegetables.
Szechuan peppers are frequently combined with hot, spicy red chili peppers in authentic Szechuan cuisine; Tea-Smoked Duck, Mapo Tofu and Ma La Hot Pot are popular examples. Ginger, garlic and star anise often appear with Szechuan peppers as well. Chinese Five-Spice Powder is also made from Szechuan peppers, along with star anise, cinnamon, clove and fennel.
This Chinese pepper was banned in the US from 1968 until 2005 because the berry shells can carry incurable citrus canker disease. This may be a danger to citrus crops but not to humans. During the ban, fans sometimes obtained smuggled Szechuan peppers or else went without; most substitutes lacked a similar flavor and effect. This led to the development of Americanized dishes such as Kung Pao Chicken, which are missing the Szechuan peppers found in authentic Chinese recipes. In 2005, the US Food and Drug Administration (FDA) and the US Department of Agriculture (USDA) lifted the ban. They decreed that a Szechuan pepper could be safely imported as long as it was heat-treated before shipment — 160 degrees Fahrenheit (71 degrees Celsius) is considered sufficient to kill the highly-contagious canker bacteria.
A variety of the species Zanthoxylum can produce a Szechuan pepper. These species may grow in parts of China, Japan, the Himalayas, Southeast Asia and North America; only a few are used for seasoning, however. Each region appears to have its own name for the fruit — Nepal pepper, Indonesian lemon pepper and Japanese pepper are common, along withfagara, aniseed pepper and sprice pepper.