In a large bowl, combine the first 5 ingredients. Shape the mixture into 4
patties, each about 1" thick. Heat 1 tablespoon of the butter with the oil
and mustard in a heavy skillet over moderate heat for about 1 minute. Add
the patties and cook, uncovered, 3 minutes on each side for rare, 4 minutes
for medium, and 6 for well done. Remove the patties to a warm platter. Add
the lemon juice and Worcestershire sauce to the skillet, and stir for 30
seconds. Remove the skillet from the heat, and stir in the parsley and the
remaining butter. Pour sauce over patties and serve.
