Caul Fat

Caul fat is the omentum, the membrane that drapes over the abdominal organs, and in a pig it comes out as a large sheet of translucent tissue webbed with fat in a pattern that genuinely looks like lace. It is not a fat depot like back fat; it is a membrane with fat deposited along its vessels.

Its use is entirely as a wrapper, and it does three things at once. It holds a loose forcemeat together without a casing, so a crépinette, a faggot, a French caillette or a Corsican figatellu can be shaped by hand and will keep that shape. It bastes: the fat renders during cooking and runs through the meat it surrounds, which is why caul-wrapped items stay moist where a bare patty would dry. And it browns to a thin crisp skin, then largely disappears, so the finished item looks like it was never wrapped at all.

That disappearing act is the point of difference from every other casing. A natural casing stays and is eaten as a skin with snap. Caul melts. Where a recipe wants the shape and the basting without the bite of a casing, caul is the answer and nothing else does the same job.

It is also used for barding. A lean roast, a terrine or a pâté lined with caul is protected from drying and gains fat without a slab of it sitting visibly on top. Many classical terrines are lined with caul rather than bacon for exactly this reason: it holds the loaf, it renders in, and it does not add its own flavour.

Handling has one requirement. Caul arrives folded and often salted or frozen, and it tears easily when cold and dry. It is soaked in tepid, lightly salted or acidulated water until it relaxes and opens, then spread out flat, patted dry and cut to size. Rushed, it shreds. Any thick vessels or membrane that will not soften are cut away.

It has no preservative function and does not exclude air over any useful period, so a caul-wrapped item is a fresh or cooked product, not a cured one.