Combine beef and soy sauce in a small bowl; marinate 5 minutes.
Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add the beef, and sauté 2 minutes. Add the sliced bell pepper and the next 5 ingredients (bell pepper through garlic) to skillet. Cover, reduce heat, and simmer for 15 minutes.
Combine beef broth, water, and cornstarch, and stir with a whisk. Add to beef mixture, and simmer, covered, 30 minutes or until beef is tender. Serve over rice.