In a large bowl, combine steak, potatoes, olive oil, garlic, onion powder, oregano, salt, and pepper; toss to combine.
Divide steak and potatoes between 6 (12x12-inch) sheets of foil, then wrap foil tightly around the contents to form foil packets.
Preheat grill to high heat.
Grill over high heat about 10 minutes on each side or until steak and potatoes are cooked through. Or, bake at 425°F about 20-25 minutes until cooked through to desired doneness.
Note: For medium steak doneness, boil potatoes 5 minutes before combining with the other ingredients.