Rinse the corned beef and place it in a baking dish with 1 cup of water. Cover the dish very tightly with foil. Bake for 2 hours and then pour off any liquid in the dish.
Combine the red currant jelly, brown sugar, and soy sauce in a small bowl; brush evenly over the corned beef.
Bake, uncovered, basting occasionally with any pan juices, until the meat is tender, 25 to 30 minutes. Let rest for 10 minutes before slicing the corned beef against the grain. Serve hot or at room temperature.