Cut zucchini in half lengthwise; cut lengthwise into 1/4-inch-thick slices. Peel eggplant, and cut into 1-inch cubes. Sprinkle eggplant with 1 tsp. salt, and let stand 30 minutes.
Meanwhile, stir together olive oil, next 3 ingredients, and remaining 1 tsp. salt. Let stand 20 minutes. Rinse eggplant, and pat dry.
Preheat grill to 300° to 350° (medium) heat. Combine eggplant, zucchini, bell pepper, onion, and olive oil mixture in a large bowl, tossing to combine. Grill vegetable mixture in a lightly greased grill wok or metal basket, stirring occasionally, 15 minutes. Stir in tomatoes, and grill 3 more minutes or until tomatoes are tender. Garnish, if desired.