Step 1

Preheat the Oven - Set the oven rack to the center position. Preheat to 350°F (177ºC).

Step 2

Prepare the Meat - Remove the corned beef from the package, discarding the spice packet. Dry the surface with paper towels. Place the beef fat-side up on a wire rack set on top of a roasting pan. Add about 1 inch of water to prevent the juices from burning while cooking.

Step 3

Make the Glaze - Combine whole grain mustard, Dijon, and honey. Evenly spread 3 tablespoons (about half) of the mixture on top of the meat.

Step 4

Cover the Meat - Sprinkle 2 tablespoons of brown sugar over the top. Then loosely cover the pan completely with foil.

Step 5

Bake - Bake the corned beef until tender and the internal temperature reaches 160ºF (71ºC), about 75 minutes. Add more time as needed to cook thoroughly.

Step 6

Remove and Glaze - Carefully remove the pan from the oven and transfer the corned beef to a baking sheet lined with foil. Set oven temperature to broil. Glaze with the remaining mustard mixture, then sprinkle with 2 tablespoons of brown sugar.

Step 7

Broil - Cook until the top of the meat turns golden brown, about 3 to 5 minutes.

Step 8

Rest, then Slice - Remove beef from the oven and allow it to rest for 10 minutes on a cutting board. Slice against the grain and serve immediately.