Rinse steak and pat dry. Cover and pat tri-tip with the seasoning salt . Put in a large resealable plastic bag and pour in whiskey and cider to coat meat. Marinate in refrigerator for 1 to 3 hours.
For the Oven:
Preheat the oven to 450 degrees F. Remove steak from refrigerator, let come to room temperature (approximately 20 to 30 minutes).
Remove the meat from the marinade. Discard the marinade. Place the tri-tip, fat-side up, on a rack in a shallow roasting pan. Roast for 30 minutes, then begin checking the internal temperature on an instant-read thermometer: for medium-rare, 135 to 140 degrees F and 140 to 145 degrees F for medium. Let stand 5 to 10 minutes before slicing.
Set up grill for indirect cooking over medium-high heat. Oil grate when ready to start cooking. Remove steak from refrigerator, let come to room temperature (approximately 20 to 30 minutes).
Remove steak from marinade, discard marinade. Place steak on hot oiled grill and cook 30 to 35 minutes per side for medium or until internal temperature reaches 145 to 150 degrees F on an instant-read thermometer. Transfer steak to a platter and let rest 5 to 10 minutes. Slice thinly across the grain and serve hot or warm.