Stir together brown sugar, soy sauce, Worcestershire, lemon juice, garlic powder & whiskey. Place steaks in a big zipped bag. Pour in marinade and seal bag. Refrigerate for at least 1 hour.
Remove meat from marinade and grill to desired done-ness.
Which should be on the rarer side of medium, by the way. Don’t waste a good Schinkel Steak.