Place corned beef in a large pot and add water to cover. Bring to a boil and then lower to a simmer. Cover and cook until a fork goes in easily, about one hour.

Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). Remove corned beef from pot and place in a 9×13-inch baking pan.

Mix the rest of the ingredients in a small bowl and pour over the corned beef. Bake for 35–40 minutes. Pull apart with two forks, or allow to cool, and slice.