Pat the beef brisket dry and trim excess fat. Rub with salt, pepper, paprika, brown sugar, garlic powder, onion powder, cumin, chili powder, and thyme.

Heat olive oil in a skillet and sear the brisket for 3–4 minutes on each side until browned. Transfer to the slow cooker or Dutch oven.

Sauté sliced onions in the same skillet for 3–4 minutes, then add garlic cloves for another minute.

Deglaze the skillet with beef broth, then stir in tomato paste, Worcestershire sauce, and apple cider vinegar. Pour over brisket and add bay leaves.

Cook on Low for 8–10 hours or High for 5–6 hours until fork-tender, or bake covered at 300°F for 3.5–4.5 hours.

Let the brisket rest for 20 minutes, strain the cooking liquid, and reduce it if desired for gravy. Slice against the grain and serve with gravy.