Toast bread. Rub one side of hot toast with cut side of garlic. Heat oil in nonstick skillet over medium-high heat; add onion and cook, stirring until tender. Add tomato, oregano and pepper, stir. Spoon tomato mixture over garlic side of hot toast and serve immediately. Alternatively, sprinkle with Parmesan and broil for 1 minute. Per serving (2 slices): 105 cal; 2 g fat; 1 mg cholesterol; 190 mg salt.