Combine cola, oil and steak seasoning in a large resealable plastic bag. Add steaks and onion. Marinate in refrigerator, at least 30 minutes.
Remove steaks and onion from marinade; discard marinade.
Grill steaks and onions over direct medium heat with the lid closed as much as possible. Grill 16 to 20 minutes, turning once, until steaks reach desired doneness and onions are tender and charred.
Remove from grill and let steak rest 5 minutes before serving.
Tips
Prep your steak with Weber® Chicago Steak Seasoning.
