Start by patting the beef brisket dry with paper towels, ensuring there’s no excess moisture. Trim the fat cap to 1/4 inch and season all sides with the spice mix.

Heat a large skillet over medium-high heat and add olive oil. Sear the brisket in the skillet for 3 to 4 minutes on each side until a rich brown crust forms.

In the same skillet, add the sliced yellow onions and sauté for 3 to 4 minutes, then add the smashed garlic cloves and cook for an additional 30 seconds.

Pour in the beef broth, tomato paste, Worcestershire sauce, and apple cider vinegar to the sautéed onions. Let simmer for about 1 minute, then pour over the seared brisket in the slow cooker, adding bay leaves.

Cover and cook on Low for 8 to 10 hours or High for 5 to 6 hours until fork-tender. For Dutch oven, bake at 300°F for 3 1/2 to 4 1/2 hours.

Once done, let the brisket rest for 20 minutes. Strain the cooking liquid, discard bay leaves, and slice brisket against the grain before serving with gravy.