Whisk together 2 tablespoons cornstarch, ginger, beef broth, soy sauce, and, if desired, red pepper; set aside.
Combine remaining 2 tablespoons cornstarch, salt, and pepper; dredge steak in mixture.
Heat vegetable oil and sesame oil in a large skillet over high heat 3 minutes; add steak and garlic, and saute 4 minutes or until browned.
Add bell pepper and onion; saute 8 minutes or until tender. Stir in broth mixture; reduce heat, and simmer 3 to 5 minutes or until thickened. Serve over hot cooked rice.