Place roast in a deep roasting pan, fat side up. Puncture meat with tenderizing tool or meat fork; pour vinegar over. Let stand for 15 minutes. Sprinkle with salt and pepper. Add water to pan. Cover and bake at 400 degrees for 3 1/2 hours or until meat is tender, additional additional water if needed. About 15 minutes before roast is done, uncover to brown the top. Remove roast from pan and keep warm; skim fat from pan juices. Measure the juices, adding water if needed to equal 3 cups. Mix flour and cold water until smooth; stir into pan juices. Cook and stir until thickened and bubbly. Cook and stir 1 minute more. Stir in browning sauce. Season with salt and pepper. Serve gravy with roast.