01 - Pat brisket dry using paper towels. Season all sides evenly with salt, black pepper, and smoked paprika.
02 - Arrange sliced onions, carrot chunks, and celery pieces at the base of the slow cooker. Sprinkle minced garlic over the vegetables.
03 - Whisk together beef broth, barbecue sauce, tomato paste, Worcestershire sauce, brown sugar, dried thyme, and remaining smoked paprika in a mixing bowl.
04 - Place the seasoned brisket atop the vegetables in the slow cooker. Evenly pour the sauce mixture over the beef. Cover and cook on low for 8 hours until fork-tender.
05 - Transfer brisket to a cutting board. Allow to rest for 10 minutes, then slice against the grain.
06 - Remove excess fat from cooking juices. Serve sliced brisket with vegetables, drizzle with sauce, and garnish with fresh parsley if desired.