Two hours before roasting the brisket; rub the vinegar over all sides of the meat, wrap in plastic wrap and refrigerate.
Preheat oven to 325F; line roasting pan with aluminum foil. Score top and bottom of meat with diagonal cuts, creating one inch diamond marks. Mix together the ginger, white pepper and salt; rub on both sides of meat. Place meat in pan and roast for 15 minutes.
Mix together sauce, garlic and onion; turn meat over in pan, baste top and sides of meat with sauce mixture making sure to get sauce into score marks. Return to oven for 30 minutes; turn over meat, baste and roast for another 30 minutes for medium-rare. For medium; repeat turn and baste process, roast for 30 minutes more. For medium-well; repeat turn and baste process, roast for 30 minutes more.
Remove meat to cutting board; rest for 5 minutes before slicing; spoon sauce from roasting pan over meat. Serve with fried rice; when making rice, add one teaspoon of Hoisin sauce for every three servings to boost the flavor.