Rinse the corned beef brisket in cool water and place it into a large Dutch oven.

Generously coat the beef with brown sugar on all sides.

Pour Irish stout beer around the roast, followed by beef stock.

Ensure the liquid covers the brisket by about 1 inch; add more beer if needed.

Place the onion, garlic, bay leaves, spice packet from the corned beef, and peppercorns into the liquid.

Bring the mixture to a boil, then reduce the heat to low and cover the Dutch oven.

Simmer for 2 1/2 hours, turning the brisket over in the beer mixture every 30 minutes.

Place the potatoes and carrots around the roast, cover, and simmer for 20 minutes.

Add the cabbage wedges and simmer until tender, about 10 more minutes.

Check that the brisket easily pulls apart with your fingers or a fork.

Transfer the vegetables to a serving bowl and place the corned beef on a serving platter.

Let the meat rest for 10 minutes before slicing across the grain to serve.