Combine seasoning ingredients in small bowl; remove and reserve 2 tablespoons. Press remaining seasoning evenly onto beef steaks; set aside.
Combine reserved seasoning, oil and salt in large bowl. Add potatoes; toss to coat.
Place steaks on grill over medium, ash-covered coals; arrange potatoes around steaks. Grill steaks, covered, 10 -14 minutes (over medium heat on preheated gas grill, 9 - 14 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally.
Grill potatoes 14 - 17 minutes (over medium heat on preheated gas grill, 13 -15 minutes) or until tender, turning occasionally.
Carve steaks into slices; season with salt, as desired. Sprinkle green onion over potatoes. Serve potatoes with Sour Cream and Onion Sauce for dipping, if desired.
Sour Cream and Onion Sauce: Combine sour cream and green onion. Sprinkle with smoked or Spanish paprika, as desired.