Place corned beef on foil. Cover with coarse pepper. Put onion slices all
over it, using toothpicks where necessary to hold them. Secure foil across top,
then sides, leaving air space inside, but so no liquid can leak out. Place in
pan at least 2 inches deep.
Bake at 350 degrees F for 3 hours (no matter what size).
Boil cabbage and potatoes in pan juices drained from pan.