In a saucepan, combine all the ingredients for the court-bouillon and bring to a boil for 15 minutes. Cover and let cool to allow the flavors to infusion.Bring to a boil again, then plunge in the mackerel fillets.Skim and let poach for 10 minutes.Drain the fillets, remove the skin, bones, and black parts.Mix all the ingredients for the compote and the crumbled mackerel fillets.Cut a lid off the apples and hollow them out with a Parisian spoon.Chop the apple flesh and add it to the mackerel compote.Fill the apples, making the filling overflow a little, then put the apple lid back on.Wrap with raffia.Refrigerate for at least 2 hours before serving with crackers, grissini, or Melba toast.