My friend gave me this recipe which she got from a friend who got it from allrecipes.com. They are so good and so easy! I don't usually use a four pound roast for us -- just one or two but the same amount of broth. I use the leftover broth as a base for soup or gravy for a pot pie.
Remove and discard all visible fat from the roast and brown on all sides in a frying pan with a little oil. Place in slow cooker.
In a medium bowl, combine all ingredients and pour over the roast. Add enough water to almost cover roast. Cover, and cook on low heat for 10 to 12 hours or until meat is very tender.
Remove meat from broth. Reserve broth. Shred meat with a fork and distribute on bread for sandwiches. Serve with broth for dipping. You may want to slightly toast the bread before making your sandwiches.