In a large bowl, combine 1/2 cup oil, the vinegar, salt, and pepper; mix well. Add the beef and toss to coat evenly; set aside. Place the remaining 2 cups oil in a 2-quart fondue pot; heat on the stovetop over medium heat until the oil reaches 360 degrees F. (hot but not smoking). Place the fondue pot over the heat source where it is being served. Using fondue forks or skewers, carefully place each beef cube in the hot oil for 15 to 20 seconds or longer for desired doneness. Remove beef from the oil, let cool slightly, and enjoy.
SERVING TIP: This is great served with horseradish sauce and/or mustard sauce for dipping.