Place the sliced onion and minced garlic in the bottom of the slow cooker.
Rub the brisket with smoked paprika, salt, and pepper, then set it on top of the onions.
Pour the beef broth around the meat.
Cover and cook on low for 8 hours until the brisket is fork-tender.
Remove the brisket to a cutting board and shred it with two forks.
Return the shredded beef to the slow cooker and stir in the barbecue sauce until evenly coated.
Spoon the beef mixture onto the sandwich buns and serve.