What is caul fat and what is it used for? 

Caul fat is the fatty layer surrounding the intestines of cows, sheep and pigs. Its biological name is the epiploon or omentum. It is used in butchery, sausage making and cooking. It is a lacy translucent layer, most often sold for making sausages, pâtés, terrines, etc. so that they hold their shape when cooked. It is also used to wrap roasts for cooking, since it keeps them moist without adding as much fat as barding. Before using, it's recommended that caul fat be soaked for a few minutes in lukewarm water to soften it.