Remove the ham from the packaging and discard whatever glaze it came with. Quickly rise it with cool running water and pat it dry.
TIP: For spiral cut ham, there is no need to score the top. For the ham that is not cut, make sure to score the outside skin first, before adding the mustard mixture. Make cuts across the skin that are about 1/4-1/2 inch deep, forming diamond shapes.
Combine maple syrup and Dijon mustard in a small bowl and rub the ham all over with the mixture.
Prepare the smoker:
Set up your smoker and get it to a steady 225°. Place a water pan either on the grate below the meat or next to it, depending on your smoker and your smoker set-up.
Insert digital meat thermometer probe into the ham and place it cut-side down directly on the grate. Make sure to place the ambient temperature thermometer on the grate, near the meat but not touching the meat. Close the lid right away so the temperature doesn’t get too low.
Prepare Ham Glaze:
TIP: You can prepare the glaze when the ham is getting close to glazing temperature.
Preheat a sauce pot over medium heat and add butter. Once butter is melted, add diced onion and sauté until softened.
Add minced garlic and let it cook for a few seconds, until fragrant.
Whisk in remaining glaze ingredients and bring the mixture to simmer. Lower the heat slightly and let it simmer for about 15 minutes. NOTE: the glaze will look thin while it's hot but it thickens as it cools.
Smoke the ham:
Smoke the ham until it reaches 130°. Take it off the smoker (and close the lid so the temperature doesn’t go down) and glaze it generously with about half of the glaze. TIP: For spiral-cut ham, you can get in between the layers to add more flavor inside.
Place the ham back into the smoker and let it cook until reaches 140°.
Take the ham off the smoker and tent it with a sheet of aluminum foil. Let it rest for about 20-30 minutes (depending of the size.)