Prep the Brisket: Dry the brisket with paper towels. Mix the salt, pepper, paprika, onion, and garlic powders in a bowl. Rub this mixture all over the brisket.
Sear the Brisket: In a skillet over medium-high heat, sear the brisket in olive oil until golden (about 3-4 minutes per side), then place in the slow cooker.
Prepare the Sauce: Sauté onion and garlic in the skillet until soft. Add beef broth to deglaze, then the vinegar, sugar, tomato paste, and Worcestershire sauce. Simmer for 2 minutes before pouring over the brisket.
Slow Cook: Add bay leaves and thyme to the slow cooker. Cook on low for 8-10 hours until tender.
Rest and Serve: Let the brisket rest before slicing. Serve with gravy made from the cooking juices.