1Remove fat from beef. Cut beef with grain into 2-inch strips; cut strips across grain into 1/8-inch slices.
2Spray 12-inch nonstick skillet with cooking spray; heat over medium-high heat. Add beef, onion and bell pepper; cook 4 to 5 minutes, stirring frequently, until beef is no longer pink.
3Stir in all remaining ingredients, breaking up tomatoes. Cook about 5 minutes, stirring occasionally, until zucchini is tender and mixture is hot.