In a roasting pan or dutch oven, add beef pieces, chopped onion, envelope dry onion soup mix, pepper, and butter. Add enough water to cover meat mixture, about an inch over top of meat. Cover roaster tightly with aluminum foil. Bake at 325º for 2 1/2 to 3 hours. Remove pan form oven. With a slotted spoon, remove meat to a bowl. Set pan aside. Do not drain water/juices from pan. Shred meat with two forks when cool enough to handle or shred with clean fingers. (I prefer to shred my beef with my clean fingers)

Return meat back to pan and pan juices. Place pan on stove top and heat on medium to medium-high heat. Let mixture boil gently until liquid is reduced by half, stirring constantly.

Allow to cool. Refrigerate overnight. Before re-heating, skim off fat that has settled on top.

You can re-heat beef in a saucepan on the stove top or place beef in a crock-pot and cook on low until hot. Serve with Garlic Bread or Crusty Rolls.