Put the corned beef in a large, heavy pot and cover with water (you can use a crock pot if you'd like). Add all the remaining ingredients. Bring to a boil and skim all the foam that rises to the surface.
Lower the heat so that the water bubbles occasionally rather than constantly. Cook, turning every 30 minutes or so, for about 2 hours. Pierce with a thin-bladed knife, such as a boning knife; the meat will probably still be fairly tough, but it's time to begin checking.
Check every 15 minutes; when the corned beef allows the knife to pass into the middle without much resistance, it is ready. Drain; if you like, put the meat into a 300°F. oven for 10 minutes to dry out the exterior a little. (Or wrap it carefully in tin foil and refrigerate for up to 2 days; reheat at 300°F for 30 minutes in the foil; unwrap and heat about 15 minutes more.)
Slice (across the grain, as you would brisket), and serve.