Heat the oven to 300°F. Add the ham to a roasting pan with a rack, then add about 1 cup water to the bottom of the baking dish (or enough to create a thin layer coating the bottom). Roast for about 1 hour and 15 minutes, or until an instant-read thermometer reaches an internal temperature of 115°F.
Meanwhile, stir together the mustard and jam to create the glaze.
Once the ham has warmed through, remove from the oven and raise the heat to 375°F. Paint the ham with about 2/3 of the glaze. Cook for another 15 to 25 minutes, until the slices are crisped and the glaze is deeply browned. Remove from the oven and paint with the remaining glaze.
Emma is the food editor at Food52. Before this, she worked a lot of odd jobs, all at the same time. Think: stir-frying noodles "on the fly," baking dozens of pastries at 3 a.m., reviewing restaurants, and writing articles about everything from how to use leftover mashed potatoes to the history of pies in North Carolina. Now she lives in Maplewood, New Jersey with her husband and their cat, Butter. Stay tuned every Tuesday for Emma's cooking column, Big Little Recipes, all about big flavor and little ingredient lists. And see what she's up to on Instagram at @emmalaperruque.