Sichuan pepper is the dried, reddish-brown husk of the berry of the prickly-ash tree Zanthoxylum bungeanum, a spice that is neither a true pepper nor a chilli but a member of the citrus family. It carries a bright, citrus-floral, faintly resinous aroma, but its real signature is a physical sensation rather than a flavour: a buzzing, fizzing, tongue-numbing tingle the Chinese call má. That numbing quality is the má half of Sichuan cooking's defining málà (numbing-and-hot) sensation — the husk supplies the tingle, dried chillies the heat — and it is the soul of dishes such as mapo tofu, mala hotpot and dry-fried chicken.