Set half the patties aside for "lids." Sprinkle remaining patties with salt and pepper, then spread with prepared mustard, leaving 1/2-inch margin for sealing.
Top with a mound of Pickle Filling.
Cover the filling with "lids," sealing edges well.
Place on greased grill or spread both sides with soft butter or margarine.
Season top side with salt and pepper.
Broil over hot coals about 10 minutes; turn; broil about 10 minutes more or till done to your liking.
Season second side.
Slip patties into hot buttered buns.