Sansho pepper (山椒) is a Japanese seasoning powder made from the ground berries of the prickly ash tree. The powder has a peppery-lemon flavor with a long residual heat. Sansho powder is used to season sushi and make various Japanese noodle dishes mildly hot and fragrant.
The whole fresh leaves, 木の芽 kinome, are used to flavor vegetables, especially bamboo shoots, and to decorate soups. Typically the young shoots are used in this way, giving an aromatic lemony flavor to food. They are used to denote spring seasonality in food. The buds, seeds, flowers, and hulls are also used.
It’s also known as Szechuan pepper, Chinese pepper, Japanese pepper.