To make the glaze, combine the garlic marmalade, mustard, sugar, zest and juice in a medium saucepan and bring to a simmer over low heat. Cook for 15 minutes, stirring occasionally, until slightly thickened and let cool for 30 minutes. Bring to room temperature before using. This glaze can be made several days in advance and refrigerated.
Heat your Hybrid Fire Grill to 350°F. Place the ham in a medium roasting pan or a heavy-duty disposable baking pan, fat side up. Cut cross-check slits 1/2-inch deep into the meat of the ham and stud with cloves if desired. Add 1 cup of water to the bottom of the pan, cover with foil and bake on the grill grates with the cover closed for 1 hour.
Remove the foil and continue baking until the fat becomes light golden brown, about 30 minutes longer.
Increase the heat of the grill to 400°F. Cook for an additional 45 minutes and begin brushing the ham with the glaze every 10 minutes until the thickest part of the ham registers 160°F. The only thing left to do is slice and enjoy!
