coleslawor red cabbage and scallions, for serving, optional
To make the dry rub:
In a small bowl, whisk together brown sugar, Worcestershire sauce, pepper, dry mustard, garlic powder, liquid smoke, and salt. Rub all over brisket.
Place in a gallon-sized zipper-top plastic bag or in a dish with a cover. Refrigerate at least 30 minutes or overnight.
To make the brisket:
Transfer brisket to slow cooker. Cover and heat on HIGH for 8 to 10 hours.
Preheat broiler on HIGH. Remove brisket from slow cooker and transfer to a rimmed baking sheet or roasting pan. Brush brisket with barbecue sauce on all sides. Broil until sauce is sticky and bubbly, about 1 to 2 minutes.
Remove brisket to a cutting board and tent with foil for 10 minutes. Slice brisket thinly across the grain. Serve on grilled Texas toast or soft rolls coleslaw or red cabbage and scallions, if desired.