Heat Oil In Large Nonstick Skillet Over Medium-High Heat. Sprinkle Chicken On Each Side With Garlic Salt And Pepper. Place In Skillet; Cook 6 Minutes To Brown, Turning Once. Remove From Skillet; Keep Warm. Place Zucchini And Onion In Skillet. Cook 5 Minutes Or Until Tender, Stirring Occasionally. Stir In Undrained Tomatoes. Return Chicken To Skillet. Cover; Reduce Heat To Medium-Low And Simmer 10 To 12 Minutes Or Until Chicken Is No Longer Pink In Centers (165 Degrees F). Serve Vegetable Mixture Over Chicken.