Remove pin bones. Cut into 2 equal pieces.
Combine salt, pepper, sugar and allspice (and brandy). Rub on filets. Make a
sandwich of the filets, putting the dill in the middle.
Cover with plastic and a heavy (5lb.) weight, and refrigerate for 24 hours. Flip
the filets, cool another 24 hours.
Sauce:
Combine mustard, vinegar, sugar. Whisk in the oil, until thick. Season with salt
and pepper, and the fresh dill.