Preheat oven to 375°.
To prepare chicken, combine first 4 ingredients in a medium bowl. Add chicken, tossing to coat. Arrange chicken in a single layer on a baking sheet coated with cooking spray. Bake at 375° for 15 minutes or until chicken is done and lightly browned, stirring once.
To prepare salad, combine vinegar and next 7 ingredients (through minced garlic) in a food processor; process until well combined.
Combine tomatoes, green onions, and salad mix in a large bowl; add vinegar mixture, tossing to coat. Place about 1 cup salad mixture on each of 4 plates; top each serving with about 1 cup chicken.