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 taste. The onions may be prepared a day ahead of time and reheated before serving.
Heat the grill or broiler. Remove the chops from the marinade and pat dry. Brush with oil and lightly sprinkle with salt and pepper. Grill or broil 4 to 6 minutes each side until cooked through but not dry. The meat will remain somewhat pink in the center due to the marinade.
To serve, spoon the warm onion mixture onto each serving plate and top with a chop. Serve with roasted or fried potatoes or Grilled Radicchio. The radicchio is a nice accompaniment as its bitterness contrasts well with the sweetness of the onions and pork.