Instructions:

1. Sear the Brisket:
   Heat olive oil in a skillet over medium-high heat. Brown the brisket on all sides, then transfer it to the slow cooker.
2. Sauté the Onion and Garlic:
   In the same skillet, sauté the sliced onion and minced garlic for 3-4 minutes until softened.
3. Prepare the Sauce:
   In a bowl, combine the beef stock, BBQ sauce, apple cider vinegar, brown sugar, Worcestershire sauce, smoked paprika, and dried thyme. Bring the mixture to a simmer.
4. Add the Sauce to the Brisket:
   Pour the sauce over the brisket in the slow cooker. Season with salt and pepper to taste.
5. Slow Cook:
   Cook the brisket on low for 8-10 hours, or until the meat is tender and the flavors are well infused.
6. Rest and Serve:
   Allow the brisket to rest for 10 minutes before slicing. Serve with the rich BBQ sauce for an extra boost of flavor.