PREHEAT oven to 350°F. Place onions in roasting pan. Top with meat.
MIX remaining ingredients; pour over meat. Cover with foil; pierce foil in several places with sharp knife or fork to vent.
BAKE 3-1/2 to 4 hours or until meat is cooked through (160°F) and tender. Let stand, covered, 10 min. before slicing. Serve with the meat drippings.