2-1/2 pounds corned beef with spice packet
1 celery stalk, trimmed, cut into 1/2 inch diagonal slices
1 carrot, peeled, cut into 1/2 inch diagonal slices
1 small yellow onion, cut into thin wedges
2 cloves garlic, crushed with the side of a knife
1 can (28 ounces) Italian plum tomatoes in juices
1/2 head (1 pound) green cabbage, cut into 4 wedges, cores slightly trimmed
10 small red potatoes, cut in half
2 teaspoons whole-grain mustard
1. Unwrap the corned beef and pat dry with paper towels.
2. Arrange the celery, carrot, onion, and garlic in a 13 x 9-inch roasting pan. Place the corned beef on top of the vegetables. Sprinkle the contents of the spice packet over the corned beef and rub into the surface of the meat. Add the tomatoes; fill the empty tomato can with water and add to the pan. With kitchen shears cut the tomatoes into 1-inch chunks.
3. Cover the pan tightly with heavy-duty foil and grill over Indirect Medium heat for 2 hours. Remove the pan from the grill. Add the cabbage wedges and potatoes around the corned beef and spoon the cooking juices on top. Cover the pan with foil and continue grilling over Indirect Medium heat until the corned beef, potatoes, and cabbage are tender, about 1 hour more. Transfer the corned beef to a cutting board and spread the mustard on top. Let stand 5 minutes before carving meat across the grain into 1/2-inch slices. Serve corned beef slices with the cabbage and potatoes, with juices spooned over all, along with grilled rye bread, if desired.