Siu mei is the Cantonese tradition of roasted and barbecued meats displayed hanging in restaurant windows — char siu (barbecued pork), siu yuk (crispy roast pork belly), siu ngaap (roast duck), and siu gai (roast chicken). Each requires different technique: char siu is marinated, roasted, and repeatedly glazed until lacquered. Siu yuk depends on perfectly crispy skin through a boiling water blanch, salt-drying overnight, and roasting at two temperatures. These are the techniques behind the Chinatown window displays that define Cantonese food globally.
Char siu: pork shoulder or neck marinated in maltose, hoisin, soy sauce, five-spice, red fermented tofu (the source of the red colour, not food colouring). Roasted at high heat, basted with marinade every 10 minutes to build lacquered layers. Final blast under a broiler to caramelise the glaze. Siu yuk: score the skin with a sharp knife in tight rows, blanch the whole belly in boiling water, rub skin with salt and vinegar, refrigerate uncovered overnight to dry completely. Roast at 180°C for 45 minutes, then blast at 230°C+ or under broiler until the skin puffs and crackles. The skin should shatter like glass. The meat should be juicy underneath.
For siu yuk at home: poke the skin all over with a sharp skewer (not a fork — too large), blanch, salt and vinegar the skin, refrigerate on a rack uncovered for 24 hours minimum. The drier the skin, the better the crackle. For char siu: the glaze should be thick enough to coat the back of a spoon before basting. If you can find maltose (available at any Asian grocery), it's the key to the glossy, sticky-sweet finish that sugar alone can't achieve.
Char siu: not basting frequently enough — the lacquer builds in layers. Using honey instead of maltose — honey burns at a lower temperature. Siu yuk: not drying the skin long enough — moisture prevents crackling. Scoring too deep into the fat — the skin separates from the meat. Oven not hot enough for the final blast. Using lean belly — you need a thick fat layer between skin and meat.