Dice eggplant (unpeeled), discarding ends. In a large skillet, heat oil over medium-high heat. Add garlic and stir for a few seconds. Add eggplant and stir briefly to coat with oil. Add tomato sauce, bell pepper, cumin, cayenne, sugar, salt and vinegar. Cook, covered, over medium heat for 20 minutes. Uncover, raise heat and boil, stirring, until reduced to about 3 cups. Cover and chill well. Just before serving, stir in chopped cilantro. Serve with wedges of pita bread, slices of French bread, or dark pumpernikel. Or with carrot, zucchini and celery strips for dipping. This keeps very well.