This isn't corned beef but it is wonderful.
Simmer a beef brisket in salted water with a couple cut up onions till you are able to put a fork through the meat. Take it out and drain (save the water for soup base, if you'd like). Brush or roll the brisket in your favorite barbeque sauce and place in a roasting pan, roast at 325, continue brushing with barbeque sauce while it is cooking, roast until the meat it is very tender. (tip: line the roasting pan with tin foil for easy clean up). You can slice it or tear it apart for barbequed beef sandwiches. In the summer I cover it with the sauce, wrap it in foil and put it on the grill in a spot where it won't burn and leave it for a couple of hours.