Peppercorn, Sichuan pepper
Sichuan pepper is not actually a pepper, but is the husk, hull, or pericarp around the seeds from the plant Zanthoxylum simulans. It has what has been described as having lemony overtones and a numbing of the tongue. The tingly numbness is caused by its 3% of hydroxy alpha sanshool - sanshools are used as a preparation for chile. Sanshools appear to act on several different kinds of nerve endings at once, induce sensitivity to touch and cold in nerves that are ordinarily nonsensitive.
Sichuan pepper is a prime ingredient in Chinese 5 Spice, and is found in many dishes that contain chile in order to accentuate the capsacin effect.