Pull the ham from the fridge 30–45 minutes before baking so it heats evenly. Set it on a rack in a shallow roasting pan. Score the surface in a diamond pattern, about 1/4 inch deep, so the glaze penetrates the meat. Insert an oven-safe thermometer into the thickest part — keep the tip clear of bone and fat pockets to get an accurate read. Measure your glaze ingredients and have them ready before the ham goes in.

Preheat oven to 325°F. Place rack-mounted ham in oven and bake covered. Timing: 16–20 min/lb for a 7–10 lb bone-in ham; 15–18 min/lb for 10–14 lb; about 1.5–2 hours for 5–7 lb. While it bakes, whisk together a glaze of brown sugar, mustard, and a splash of vinegar or citrus juice. At the 30–45 minute mark before the estimated finish, remove the ham, brush glaze generously over the scored surface, and return it to the oven uncovered. Reapply every 15–20 minutes if you want a deeper crust. Watch closely — sugar glazes burn fast. Done when an instant-read thermometer reads 140°F–145°F in the thickest part. Check early; you can always add time.

Pull the ham at 140–145°F, tent loosely with foil, and rest 10–15 minutes before carving. This keeps slices moist. For bone-in ham: halve next to the bone, slice the boneless side evenly, then angle your knife away from the bone on the bone-in side. Don't overcook — most retail hams are already fully cooked; you're just reheating and building a crust. Above 145°F the meat dries out. Don't glaze too early or the sugar will burn.