In a 5 ½- or 6-quart slow cooker, combine brown sugar, cola, lemon juice, and mustard.
Add ham, turning to coat. Cover and cook on low-heat setting for 8 to 9 hours.
Transfer ham to a platter; cover to keep warm.
In a small saucepan, stir together the water and cornstarch. Add cooking juices from cooker. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 2 minutes more. Stir in horseradish.
Slice ham and serve with sauce. If desired, garnish with sage leaves.
Notes
Make sure your ham is fully cooked before starting this recipe.
Don’t skip the horseradish! It adds a wonderful balance to the sweetness.
Leftovers can be stored in an airtight container in the refrigerator for up to 5 days.
Feel free to experiment with different cola flavors.
For a spicier glaze, add a pinch of cayenne pepper to the sauce.