While the eggplant roasts, heat the remaining 1 tablespoon oil in a large skillet over medium-high heat. Add onion; cook, stirring often, until softened, 3 to 4 minutes. Add tomato paste, cumin, and garlic; cook, stirring constantly, until fragrant, about 1 minute. Add tomatoes, bell pepper and the reserved chopped eggplant; cook, stirring occasionally, until the eggplant is tender, 8 to 10 minutes. Remove from heat; stir in parsley, olives and vinegar.