1. Stack beef steaks; cut lengthwise in half and then crosswise into 1-inch wide strips. Combine marinade ingredients; add beef, tossing to coat. Cover and marinate in refrigerator 10 minutes.
2. Meanwhile, cook pasta according to package directions; keep warm.
3. Remove beef from marinade; reserve marinade. Heat large nonstick wok or skillet over medium-high heat until hot. Add beef (1/2 at a time) and stir-fry 1 to 2 minutes or until outside surface is no longer pink. (Do not overcook.) Remove from skillet with slotted spoon; keep warm.
4. In same skillet, combine pasta, spinach, water chestnuts, green onions and reserved marinade; cook until spinach is wilted and mixture is heated through, stirring occasionally. Return beef to skillet; mix lightly. Garnish with chili peppers.