Skate is the broad, triangular pectoral wing of a cartilaginous ray, prized as one of the great bistro fish. The flesh is sweet, mild and faintly shellfish-like, arranged in long ribbed strands that run parallel to thin ribs of soft cartilage; cooked, it lifts cleanly off that gristle in fanned sheets. With no true bones to pick, only this comb of pliant cartilage, skate is the centrepiece of the French classic raie au beurre noir — skate wing with black butter, capers and a splash of vinegar.