In a large resealable plastic bag, combine the pineapple juice, soy sauce, Worcestershire sauce, garlic powder and pepper. Add chicken strips; seal bag and toss to coat. Cover and refrigerate for 1 hour. Drain and discard marinade.

Grill chicken, covered, over medium heat for 8-10 minutes or until juices run clear, turning once.

To serve, arrange greens on four serving plates; top with tomatoes, pineapple, onions and warm chicken. Drizzle with dressing if desired.