Preheat the oven to 325 degrees F (165 degrees C). Trim excess fat off the ham and score in a diamond pattern with a sharp knife, making shallow cuts about 1 inch apart. Place in a roasting pan.
Roast for 30 minutes in the preheated oven. In a small bowl, mix together the maple syrup, red wine vinegar, Dijon mustard and mustard powder.
When the 30 minutes are up, brush 1/3 of the glaze over the ham. Bake 20 minutes, and repeat twice with remaining glaze. Let the ham stand for 10 to 15 minutes before carving.
