sansho (or Japanese prickly ash) Zanthoxylum piperitum, a deciduous spiny shrub, grows wild throughout Japan and in N. Korea and parts of China. The Japanese also cultivate it at home for culinary purposes, especially the preparation of the spice called sansho. The orange-coloured berries are harvested and dried in the sun and ground to make this. The bitter, black seeds inside are better discarded before the grinding. Sometimes the powder is combined with ordinary black pepper.
The spice has been called ‘Japanese pepper’ but its flavour is tangy rather than hot, and it has a slightly numbing effect in the mouth. Sansho is used in Japanese cooking to add a sharp note to fatty foods, eels for example. Other uses include the preparation of kiri-sansho, the cake which is a speciality of Tsuruoka. The sansho powder is blended with flour and kneaded into a cake.