In small bowl stir together 1/4 cup stock and cornstarch, set aside. In 4-quart saucepan, bring remaining stock to a boil; add noodles and cook for 5 minutes. Stir in bell pepper, peas and black pepper. When noodles are soft, stir in cornstarch slurry. Cook and stir until slightly thickened; stir in pork and butter. Heat through.