For the marinade, combine all the ingredients in a shallow nonaluminum container and stir until the sugar and salt dissolve. Add the chops, cover, and refrigerate 1 to 2 days.
For the onions, melt the butter in a large sauté pan over medium heat. Add the onions and cook very slowly until they are very soft, almost a puree, about 30 minutes. Stir in the cinnamon and salt and pepper to ta