Combine orange juice, cilantro and Mexican seasoning in small bowl. Place beef steak and 1/3 cup orange juice mixture in food-safe plastic bag; turn steak to coat. Close bag securely and marinate in refrigerator 6 hours or as long as overnight, turning occasionally.
Combine remaining orange juice mixture with sour cream and green onion. Cover and refrigerate until ready to serve. (May be refrigerated as long as overnight.)
Remove steak from marinade; discard marinade. Place steak on grid over medium, ash-covered coals. Grill, covered, 7 to 12 minutes (over medium heat on preheated gas grill, 8 to 12 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally.
Carve steak diagonally across the grain into thin slices; season with salt and pepper, as desired. Serve with citrus sauce.
Nutrition information per serving: 299 Calories; 180 Calories from fat; 20g Total Fat (1 g Saturated Fat; 6 g Monounsaturated Fat;) 79 mg Cholesterol; 174 mg Sodium; 4 g Total Carbohydrate; 0.2 g Dietary Fiber; 22 g Protein; 2.4 mg Iron; 3.8 mg NE Niacin; 0.4 mg Vitamin B6; 3.7 mcg Vitamin B12; 4.9 mg Zinc; 15.9 mcg Selenium.
This recipe is an excellent source of Protein, Niacin, Vitamin B6, Vitamin B12, Zinc, and Selenium; and a good source of Iron.