- In a large resealable plastic bag combine steak and marinade. Seal bag; turn to coat. Refrigerate 8 hours, turning bag occasionally. Remove from refrigerator 40 minutes before grilling.
- Coat grill rack with nonstick cooking spray. Preheat grill to high (400°F–450°F). For the sauce, in a small bowl combine sour cream, green onion, horseradish and mustard. Set aside until serving time.
- Remove steak from marinade; discard marinade. Grill, covered, 6–8 minutes per side or to desired doneness (145°F for medium-rare). Place steak on a cutting board; let stand 5 minutes. Thinly slice against the grain, and serve with horseradish sauce.
per serving: 310 calories, 13g fat, 5g saturated fat, 110mg cholesterol, 630mg sodium, 7g carbohydrate, 0g fiber, 4g sugars, 37g protein