Preheat your oven to 300°F (150°C).
Rub brisket with a mix of brown sugar, paprika, garlic powder, and salt.
Sear the brisket in a hot skillet until browned on all sides.
Place the seared brisket in a roasting pan.
Add sliced onions and garlic around the brisket.
Pour a mixture of beef broth and apple cider vinegar over the brisket.
Cover tightly with foil and roast for 4-5 hours.
Baste occasionally with pan juices for extra flavor.
Slice and serve with your favorite BBQ sauce and sides.