Place the brisket in a large stockpot. Cover with water and add the seasoning packet.
Bring the pot to a boil, then simmer for about 3 hours until the meat is tender. Reserve 2 tablespoons of the cooking liquid for the glaze. When the meat is done, remove it from the pot and discard the cooking liquid.
In a small saucepan, combine the orange juice, brown sugar, corned beef juice, mustard, and bourbon.
Whisk in the cornstarch until smooth. Bring the liquid to a boil and cook until the glaze has thickened, about 1-2 minutes.
Preheat the oven to 350 degrees.
Arrange the vegetables in a single layer on a roasting pan. Drizzle them with olive oil and season with salt and pepper.
Place the corned beef in the roasting pan on top of the vegetables. Apply the glaze liberally over the top of the entire corned beef.
Place the corned beef and vegetables in the oven. Glaze the corned beef every 10 minutes for 30 minutes.
Remove the corned beef from the oven and set it on a cutting board to rest for 15 minutes.
Turn on the broiler and continue to roast the vegetables until they start to brown, about 5-10 minutes.
Slice the corned beef against the grain. Serve over the roasted vegetables. Drizzle with the glaze.