1. Combine plums and sugar in a large bowl; cover and let stand at room temperature 8 hours.
2. Combine plum mixture and remaining ingredients in a Dutch oven; bring to a boil. Cover, reduce heat to medium-low, and simmer 15 minutes.
3. Uncover and cook over medium heat until reduced to 5 cups (about 1 hour), stirring and mashing fruit occasionally. Pour into a large bowl; cool completely. Discard cinnamon stick. Cover and refrigerate up to 2 weeks.