1. In small bowl, combine brown sugar, Italian seasoning, onion powder, salt and pepper. Rub onto brisket and place in slow cooker.
2. In a bowl, whisk broth, molasses, Worcestershire and, if desired, liquid smoke. Add to slow cooker. Slow cook on HIGH for 6 hours or LOW for 8 hours.
3. Carefully remove brisket from slow cooker and shred with 2 forks. In a small bowl, combine 1/4 cup water, cornstarch and vinegar. Strain liquid in slow cooker into a saucepan and add cornstarch mixture. Bring to a boil over medium-high heat and cook 3 minutes, until thickened and clear. Combine 5 cups of the sauce with brisket in a large bowl. Let stand, covered, for 15 minutes.
4. Split onion rolls and fill with brisket and coleslaw. Serve immediately.