Sansho means “mountain pepper” in Japanese, and refers to Zanthoxylum piperitum, also known as Japanese pepper, a shrub or small tree in the citrus family. The fruit of this species, a small berry that resembles peppercorns, has been used as a spice in Japan since the ancient Jomon period. Sancho has a similar flavor to its close relative, Sichuan pepper (a collective common name for several species in the genus Zanthoxylum), but with more pronounced citrus notes. Like Sichuan pepper, sansho berries turn pink when mature and split open to release their black seeds. However, sansho is most often harvested when still green, and then dried and ground. Sansho’s aromatic young leaves and flower buds are also edible.
The majority of Japan’s sansho crop is produced in Wakayama Prefecture, but this spice is grown in several other regions as well, and its flavor qualities vary depending on the conditions of the region in which it is cultivated. Takahara sansho, which is considered one of the most distinctive varieties, is named for the historical province of Hida in the northern part of modern-day Gifu Prefecture, central Honshu. Hida is a forested, mountainous region, most of whose inhabitants live along the Miya and Takahara rivers. It is the Takahara valley in particular that is known for its exceptional sansho. Takahara Sansho is grown in terraced fields adjacent to the river and its tributaries at an elevation of about 800 meters above sea level. Other important local crops include rice and cool-weather vegetables. Sansho from this area is known for having berries that are smaller and darker green than other varieties, and is highly valued for its unusually strong fragrance, which persists even with long-term storage. These qualities are attributed to the cool mountain climate, the local hot springs, and the mists that hang in the valleys. One of the benefits of growing sansho in this mountainous region is the reduced presence of swallowtail butterflies (Papilio xuthus), whose larvae eat the foliage of Zanthoxylum piperitum, sometimes stripping the plants bare. The relative absence of this pest means that Takahara sansho can be cultivated organically. Takahara sansho plants are reproduced using vegetative propagation, such as grafting, to maintain the characteristics of those plants with superior flavor. The harvest takes place between mid-July and mid-August, and the berries are dried carefully, first in the shade and then in the sun. The flesh is separated from the seeds and ground, using a stone mill or mallet, to yield a green powder. To preserve the aromas, it is best to grind sansho just before using it. The flavor of Takahara sansho has been described as peppery, minty, and lemony. It is reported that, during the Edo Period (1603-1868), the Hida Gundai (regional official) gifted Takahara sansho to the Shogun.
The production of Takahara sansho is declining due to the depopulation of the rural areas where it is grown. Most of the limited supply is sold locally, though some specialty stores in Tokyo now carry it. Sansho is already a popular specialty ingredient outside of Japan and, hopefully, raising awareness about different sansho varieties and their terroirs will help ensure that Takahara sansho continues to be grown and appreciated in the future.