Preheat your oven to 300°F (150°C).
Prepare the corned beef by rinsing it under cold water.
Pat the brisket dry with paper towels.
In a small bowl, mix the mustard seeds, black peppercorns, coriander seeds, garlic powder, onion powder, and brown sugar.
Rub the spice mixture over the brisket, covering it evenly.
Place the seasoned brisket in a roasting pan, fat side up.
Pour beef broth into the bottom of the roasting pan.
Cover the roasting pan with aluminum foil.
Roast the brisket in the oven for 3 to 4 hours.
Remove the foil and increase the oven temperature to 425°F (220°C).
Continue roasting for an additional 30 to 45 minutes, until the exterior is crispy.
Let the brisket rest for at least 15 minutes before slicing.
Slice against the grain and serve, garnished with parsley.