Preheat oven to 250?F. Unwrap ham, removing plastic wrap and plastic button on the flat side of the ham. Place ham in a roasting rack with the cut side down. Cover the roasting pan in foil.
Roast ham for 10-12 minutes per pound to warm it through. Remember the ham is completely cooked so this will warm up the ham without drying it out.
Meanwhile, make the sweet heat harissa glaze by adding all the ingredients to a small pot and stirring over medium-low heat. Bring the glaze to a slight simmer and turn heat down to low. Simmer for five minutes to allow sugar to dissolve and glaze to thicken. Remove from heat. Glaze will continue to thicken as it cools.
When ham is done roasting, remove from oven and remove foil. Heat oven to 450?F. Brush glaze over the surface of the ham, very generously.
Return ham to hot oven for 12-15 minutes.
Remove ham from the oven and allow to cool for 5 minutes before slicing. Serve.