Preheat the oven to 160ºC . Put the meat on a rack in a roasting pan, fat side up, and pour the liquid smoke around it. Seal the pan with foil and place it in the oven. Roast the brisket for 4 hours, or until it is very tender, turning once. Uncover the meat for the last 30 minutes to brown. Remove the meat from the oven and let it cool. Wrap it in plastic and refrigerate. Pour the pan juices and fat into a glass jar or bowl, cover, and refrigerate. The next day, remove the meat from the refrigerator and remove any extra fat. Pull the meat apart into small shreds. Remove the hardened fat from the pan juices. In a large pot, melt 3 tablespoons of the hardened fat over medium heat, add the onions and saute until tender. Add all of the remaining ingredients and 1 cup of the pan juices. Stir well and simmer for 20 minutes over low heat. Add the pulled meat to the sauce and simmer very slowly, uncovered, for 1 hour, stirring frequently. Add more pan juices, or water, if necessary, to keep the meat moist.