The lard or (even better) duck fat used to preserve the meat can indeed be used like butter. But, by far, the best use of the fat is roast potatoes.

Parboil peeled (preferably floury) potatoes. Whole or cut works. Àdd fat. Jiggle around in a pot to rough up the outside of the spuds. There is no such thing as too much fat, use it all. Roast until crispy and golden brown... 30 to 90 minutes depending on heat and specifics of the potato.

Serve with butter, gravy, onions, sour yogurt, etc.