Preheat the oven to 325 ° F.
Season the brisket on both sides with the Essence and 1 1/2 teaspoons of the salt.
Heat the oil in a large heavy skillet or large roasting pan over high heat. Add the meat and sear, turning once, until evenly browned, about 3 minutes per side. Transfer to a large roasting pan.
Combine the barbecue sauce, stock, and the remaining 2 teaspoons salt in a large mixing bowl and mix well. Pour the mixture over the brisket and cover tightly with aluminum foil. Bake for 2 1/2 hours.
Turn the meat over, cover again, and continue baking for another 2 1/2 hours, or until very tender.
Let stand for 15 minutes before carving. Slice the meat across the grain and serve with the pan juices spooned over each serving.