Cut pork across grain as thin as possible. Cut slices in narrow strips; set aside. Combine peanut butter, scallions, soy sauce, vinegar, sherry, pepper flakes, garlic and sugar; mix well. Heat 2 tablespoons oil in large skillet. Add pork and quickly stir-fry until it loses its pink color. Add cooked noodles, peanuts and remaining 3 tablespoons oil; toss well. Add sauce and toss to coat evenly. Serve immediately. Makes 4-6 servings.