• Preheat the oven to 325°F.

Brisket:

• Unwrap the brisket and place it fat side up inside the baking dish. If it came with a spice packet, sprinkle it over the top, then sprinkle on the black pepper and rub it in. Cover the dish with heavy aluminum foil (or a tight fitting cover) and place it in the oven for about 2 hours, then uncover and generously brush the glaze all over the brisket. Continue baking for 45 minutes, to an hour or until it reaches 145F.
  
• Check the brisket by inserting a fork in the meat. If it goes in easily, it’s ready; if it meets with resistance, bake for another 30 minutes---or up to an hour in some cases! If the brisket is tough, it hasn't cooked long enough! Once the brisket is fork-tender, remove it from the oven and let it rest, covered loosely in foil.

VEGETABLES:

• In a large bowl, lightly coat the carrots, potatoes and onion with olive oil and season with coarse salt and pepper (about 2 teaspoons salt and 1 teaspoon pepper). Gently toss to coat, and place on a baking sheet (for easier clean up, prepare the baking sheet with foil or parchment paper), evenly spread apart. Set aside.

Cabbage:

• Cut each head of cabbage in half, then quarters and remove the core and stem. Set aside.
• Turn the oven heat up to 350°F for the roasted vegetables and place them into the oven for about 20 minutes, turning them halfway through cooking. Check for tenderness with a fork, as the potatoes will take the longest to cook.
• While the corned beef is roasting, make the Balsamic Glaze.

  Combine the balsamic and the sugar in a small saucepan over medium-high heat. Stir it together and bring the mixture to a boil, then reduce to medium-low and simmer until the mixture is reduced by half and thick. Set it aside.
  

  Note: I skipped this step by buying a ready made balsamic glaze.

FOR THE CABBAGE:

• Cut the cabbage into 8 wedges. Heat the olive oil in a large, heavy skillet over medium-high heat and add the cabbage. Sear it on both sides until the cabbage gets as much color as possible, about 1 minute per side.
• Use a spatula to transfer the cabbage to a rack placed over a baking sheet. Sprinkle the cabbage pieces with salt and pepper. Pour the Guinness (or beer) into the bottom of the pan, then carefully transfer the pan to the oven. Bake the cabbage for 20 minutes, or until tender and deeper brown.
• Slice (or shred) the rested beef on a cutting board (it should be very, very tender and almost falling apart.) Then place it on a large platter alongside the cabbage wedges and the vegetables. Take generous spoons of the balsamic reduction and drizzle it all over the cabbage slices.
• Serve the corned beef next to the cabbage and roasted vegetables and enjoy!