Caul fat is the thin, lacy membrane of fat that surrounds the stomach and internal organs of a pig (and of sheep and cattle), harvested as a delicate net of translucent tissue laced with white veins of fat. Known in French as crépine, it is prized in charcuterie and traditional cookery as a natural wrapper: it holds crépinettes, faggots, sausages, pâtés and lean roasts together, then all but melts away in cooking, basting the food and leaving a burnished skin.