Squid is a fast-swimming cephalopod mollusc eaten the world over, almost always under its Italian kitchen name, calamari. Its flesh is mild, faintly sweet and clean-briny, prized as much for its springy, snow-white texture as for flavour — but that texture is a trap, turning from tender to rubbery to tender again across the cooking time, which is why squid is governed by a famous rule of thumb: cook it either very fast or very slow, and never in between.