Mustard- and Brown Sugar–Rubbed Ham with Balsamic-Roasted Onions

Ingredients

• 1 smoked cured city ham
• 1/4 cup Dijon mustard
• 1/4 cup backed brown sugar
• 2 1/2 tablespoons balsamic vinegar, divided
• 2 medium cloves garlic, minced
• Kosher salt and freshly ground black pepper
• 1 pound cipollini onions, peeled
• 2 tablespoons olive oil
• 2 tablespoons honey

Directions

1. Set a rack in the lower-middle of the oven, then heat the oven to 325 degrees F. Take the ham out of its wrapping, let it drain well, and settle it in a roasting pan with the sliced face down. With a paring knife, make a diamond design across the surface, cutting only about the top inch or so.
2. In a small bowl, stir together the mustard, brown sugar, 1 1/2 tablespoons balsamic vinegar, and garlic. Add salt and pepper, mix again, then smear that mixture over the ham, nudging it down into the scored lines.
3. Put the onions in a medium mixing bowl with the remaining 1 tablespoon balsamic vinegar, the olive oil, and the honey. Season them with salt and pepper, toss until they are coated, then move them to the baking pan and tuck them around the ham.
4. Slide the ham into the oven. Roast it for about 2 hours, spooning the juices from the pan over the top every 2o to 30 minutes, until the outside has browned and an instant-read thermometer pushed into the thickest area shows 130 to 140 degrees F. If the color is racing ahead, cover it loosely with foil.
5. Take the ham out of the oven and keep it loosely covered with foil while it rests for 10 to 15 minutes. Lift the onions out with a slotted spoon, then tip the drippings into a measuring cup. Skim the fat carefully from the drippings. Carve the ham and serve it right away with the onions and drippings.