Place sugar in a heavy skillet over medium-high heat; cook 2 minutes, stirring until the sugar dissolves. Cook 1 minute or until golden brown (do not stir). Remove from heat; gently stir in water and onion. Place in a medium bowl; cool completely. Stir in cranberry sauce, preserves, horseradish, and mustard. Cover and chill.
Heat a grill pan over medium-high heat. Add 4 ham slices; cook 3 minutes on each side or until grill marks form. Repeat procedure with remaining ham slices. Serve with cranberry Jezebel sauce.