Trim fat from pork. Partially freeze pork. Thinly slice across grain into bite-size strips. Set aside.
For sauce, in a small bowl stir together hoisin sauce, bean sauce or paste, soy sauce, and sugar. Set aside.
Pour cooking oil into a wok or large skillet. (Add more oil as necessary during cooking.) Preheat over medium-high heat. Stir-fry ginger and garlic in hot oil for 15 seconds. Add red and green peppers; stir-fry for 3 to 4 minutes or until crisp-tender. Remove pepper mixture from the wok.
Add pork to the hot wok. Stir-fry for 2 to 3 minutes or until thoroughly cooked. Push pork from the center of the wok.
Stir sauce. Add sauce to center of wok. Cook and stir until bubbly. Return pepper mixture to wok. Stir all ingredients together to coat with sauce. Cook and stir for 1 minute more or until heated through. Serve immediately over hot cooked noodles or rice. Makes 4 servings.