This recipe is adapted from Martha Stewart's Christmas: Entertaining, Decorating, Giving, an instant classic when it first appeared in 1989. Unlike a typical ham, which is tender and juicy, a country ham is dry-cured before smoking, so it is intensely salty; it's meant to be sliced paper-thin and eaten with a biscuit. Soaking the ham in several changes of water, which removes some of the saltiness, is an essential part of the preparation. Country ham is delicious served warm, at room temperature, or cold. The honey mustard and ham can be made a week and a day ahead, respectively, and stored in the refrigerator. Any leftover ham can be very thinly sliced, sealed in freezer bags, and stored in the freezer up to three months.