Drain pineapple, reserving 1/2 cup juice. Place pineapple chunks and vegetables in a large bowl; set aside. , In a small saucepan, combine reserved pineapple juice with the soy sauce, olive oil, brown sugar and seasonings; bring to a boil. Reduce heat and simmer, uncovered, for 5 minutes. Pour over vegetable mixture; cover and refrigerate for at least 1 hour, stirring occasionally. , Remove pineapple and vegetables from marinade and reserve marinade. On eight metal or soaked wooden skewers, alternately thread the pineapple, green pepper, onion if desired, mushrooms and tomatoes. , Grill kabobs for 20 minutes or until soft, turning and basting with marinade frequently. Serve with rice if desired.