Sansho (山椒) is the Japanese prickly-ash, Zanthoxylum piperitum, a thorny citrus-family shrub whose every part is used in the kitchen: the dried, ground berry husks make the fragrant green-brown powder (kona-zanshō) dusted over grilled eel, while its tender spring leaves — the bright "kinome" — are slapped between the palms and laid over soups and simmered dishes. Like its mainland cousin Sichuan pepper, it brings a lemony, minty-floral aroma over a light tongue-tingling numbness.