I usually make the glaze the night before, so I can get the ham right into the oven in the morning. Combine all the glaze ingredients in a saucepan. Bring the mixture to a boil, then lower to a simmer, and cook for about a half-hour. Strain the pan contents and discard the solids. Reduce the liquid to about a half-cup. Refrigerate if you do this in advance.
Place the ham on a rack in a disposable aluminum pan. Cut shallow gashes in a criss-cross pattern across the top half. Spoon the glaze over the ham to completely wet the surface.
Combine the brown sugar and the dry mustard and pat it all over the ham. Pour a half-cup of water into the pan. Put the ham in the oven at 350 degrees.
Spoon some of the glaze over the top of the ham at 15-minute intervals until it's all used up. Try to get some glaze on all parts of the ham. Add more water to the pan when it dries up.
Continue baking until the ham reaches an internal temperature of 160 degrees on a meat thermometer. Remove from the oven and allow to rest for a half-hour before carving.
