Aunt Tziviah’s corned beef and parsleyed potatoes

Boil a full corned beef until a fork goes easily into the meat.  Remove the meat and let rest.  Boil small potatoes or cut up and peel larger potatoes in the broth.  Slice corned beef.  When the potatoes are cooked through, drain and add ¼ cup chopped fresh parsley, ¼ cup margarine, and salt and pepper to taste.