Barbecued ham

1 lb ham, sliced thin
2 Tbsp butter, melted
1 onion, finely chopped
1/2 cup celery, chopped
3/4 cup water
1 cup catsup
1 tsp salt
1/2 can tomato sauce
1 Tbsp vinegar
1 Tbsp Worcestershire sauce
2 Tbsp brown sugar
1 tsp dry mustard
1/4 tsp pepper

Let simmer for 45 minutes to 1 hour. Or use crock pot and cook longer. After simmering, serve on rolls. This works great with leftover holiday ham.