In a medium bowl, whisk together the BBQ sauce and beef broth, then set aside.

In a small bowl, combine the dry rub ingredients: brown sugar, smoked paprika, chili powder, garlic powder, onion powder, cayenne pepper, salt, and black pepper.

Pat the brisket dry with paper towels. Then massage the dry rub all over the brisket.

Heat a large skillet over medium-high heat. Once hot, add the avocado oil and sear the brisket on all sides until browned, roughly 3-4 minutes per side.

Transfer the brisket to the bottom of the slow cooker pot and surround it with the sliced onions.

Pour the BBQ sauce and broth mixture over the brisket.

Cover with the lid. Cook on LOW for 8-10 hours for best results. If using a smaller, 2-pound brisket, reduce the cooking time to 6-8 hours.

Once cooked, remove the brisket from the slow cooker and transfer it to a cutting board. Slice or shred the meat, then return it to the slow cooker and stir it into the sauce.

Garnish with fresh parsley if desired.