Many recipes for spiral-sliced ham—which has been injected with or immersed in a brine of water, curing salt, and a sweetener; fully cooked; and smoked by the manufacturer—call for heating the ham in a roasting pan covered in foil in a 325-degree oven. But I found this approach to be flawed: By the time the center of the meat is warm, the exterior is certain to be parched.
Then there is the sweet glaze that is traditionally painted onto the ham. It’s a great contrast to the smoky, salty meat, but I’m always disappointed that it flavors only the very edge of the thin slices. What’s more, many recipes call for returning the ham to a hot oven for 20 to 30 minutes to help the sugary glaze caramelize and set, a surefire way to further desiccate the exterior.
I had a better way: I slid the ham into an oven bag and placed it in an oven set to just 250 degrees. The gentle heat warmed the interior and exterior of the ham at a similar rate. Meanwhile, the bag trapped juices, creating a humid environment that transferred heat more efficiently than dry air. In fact, when we compared two hams heated at 250 degrees—one in an oven bag and one covered in foil—the bagged ham came to temperature 25 percent (or 1 hour) faster than the foil-covered one. (That’s not just because an oven bag speeds cooking; since foil reflects heat, it actually slows down cooking.)
To fix the issues with the glaze, I started by making a generous amount of caramel on the stovetop; augmenting it with cider vinegar, pepper, and five‑spice powder; and brushing some of it onto the ham. With the caramelization step taken care of in advance, the ham needed only 5 minutes in a 450-degree oven for the glaze to develop a mahogany sheen. (I pulled the ham from the 250-degree oven when it registered 110 degrees, knowing that the final blast in a hot oven would cause the meat to climb to the desired 120 to 125 degrees for serving.) Next, I stirred some of the meaty ham juices that were trapped in the oven bag into the remaining caramel. This sweet, tart, savory sauce could be drizzled onto the slices so that every bite—not just the ones on the edge—would taste just right.