In a large Dutch oven, add corned beef along with the seasoning packet. Add the beer and enough water to just cover the beef. Add in the cinnamon sticks, garlic, bay leaves, and chili pepper, if using.

Bring to a simmer over medium-high heat, then reduce to low. Cover and cook until tender, about 4 to 5? hours.

Transfer the beef to a cutting board and rest while the vegetables cook.

Add the potatoes and carrots to the simmering liquid. Cook for 20 minutes, then add the cabbage and cook until the potatoes, carrots, and cabbage are tender, about 10 more minutes.

Slice the beef against the grain and serve with the vegetables and mustard, if using.