1. Place 1/2 of the brisket in slow cooker. Add onion.
2. Mix Seasoning, ketchup, brown sugar and vinegar until blended. Pour 1/2 of the mixture over brisket. Top with remaining brisket and seasoning mixture. Cover.
3. Cook 8 hours on LOW or 4 hours on HIGH. Remove brisket to serving platter.
4. Slice thinly across the grain. Stir sauce before serving. Serve with brisket.
Test Kitchen Tip: Be sure to use a fresh beef brisket rather than a corned beef brisket.
Slow Cooker Tip: For best results, do not remove cover during cooking.