1. Heat a grill pan over medium-high heat. Sprinkle chicken evenly with 1/4 teaspoon salt and 1/4 teaspoon pepper. Coat pan with cooking spray. Add chicken to pan; cook 6 minutes on each side or until done. Remove from heat, and chop.
2. Place tomato in a large bowl; sprinkle with remaining 1/2 teaspoon salt and remaining 1/4 teaspoon black pepper. Let stand for 5 minutes. Add chicken, bread, and the remaining ingredients to tomato mixture, tossing well to combine. Serve immediately.