For sauce, stir together undrained tomatoes, cornstarch, sugar, Italian seasoning, and red pepper. Set aside.
Spray a wok or large skillet with nonstick spray coating. Stir-fry carrots for 2 minutes. Add onion and garlic; stir-fry for 1 minute. Add green pepper and stir-fry 1 to 3 minutes more or until vegetables are crisp-tender. Remove from wok.
Add oil to hot wok. Stir-fry chicken livers for 2 to 3 minutes or until cooked through. Push livers from center of wok. Stir sauce; add to center of wok. Cook and stir until thickened and bubbly.
Return vegetables to wok; stir all ingredients together to coat with sauce. Cook and stir for 1 minute more or until heated through. Serve immediately over spaghetti. Makes 4 servings.