Score the ham in a crisscross pattern and place it into a roasting pan that has been filled with ½ inch or water. Make sure the grate is in the roaster so that the ham is not sitting in water.
Cover the roasting pan tightly with foil and bake the ham for 20 minutes per pound (my ham took two hours).
While the ham bakes, make the glaze by mixing together the peach jam, cider vinegar and mustard. Set aside until ready to use.
After two hours, remove the ham from the oven and take off the foil. Increase the oven to 425°F. Coat the ham with a thick layer of glaze and return it to the oven to bake for an additional 30 minutes, glazing it every 10 minutes or so.
Let ham rest for 30 minutes, tented with foil, prior to slicing. Enjoy!