Nem chua is a Vietnamese fermented pork "sausage" — finely pounded lean pork and thin strips of pork skin, seasoned with fish sauce, sugar, garlic and chilli, then packed with slices of raw garlic and bird's-eye chilli into small parcels and left to sour at room temperature for a few days. It is never cooked: fermentation, not heat, transforms it, turning the meat a bright cured pink and giving it a springy, snappy bite and a sharp, tangy, garlicky-hot flavour. Eaten as a snack or drinking food, unwrapped from its banana-leaf bundle and popped whole, it is one of Southeast Asia's most distinctive pieces of charcuterie.