1 (3-pound) corned beef brisket (uncooked), in brine
14 cups cold water
2 cups beef stock
2 bay leaves
4 sprigs fresh thyme
2 teaspoons black peppercorns
4 whole allspice berries
2 whole cloves
2 heads green cabbage (approx 3 pounds), cut into 8 wedges
3 chopped medium yellow onions
8 small new potatoes (about 1 1/4 pounds), halved
1/2 pound cut carrots
freshly ground black pepper
Preheat the oven to 300 degrees F.
Place the corned beef in a colander in the sink and rinse well under cold running water. Place the corned beef in a large Dutch oven with a tight-fitting lid, add water, beef stock, bay leaves, thyme, peppercorns, allspice and cloves. Bring to a boil, uncovered, and skim off any scum that rises to the surface. Cover and transfer pan to the oven, and braise until very tender, about 3 hours and 45 minutes.
Transfer the corned beef to a cutting board and cover tightly with aluminum foil to keep warm. Add the cabbage, potatoes, carrots and onion to the cooking liquid and bring to a boil. Lower the heat and simmer until the vegetables are tender, about 20 minutes.
Using a slotted spoon, transfer the cabbage to a large serving platter along with the carrots, onion and potatoes. Slice the corned beef across the grain of the meat into thin slices. Ladle some of the hot cooking liquid over the corned beef and season with ground black pepper. Serve immediately with whole-grain mustard or horseradish sauce.