Grind the duck, pork, pork fat, and bacon using the fine cutting blade of a meat grinder. Place in a bowl and set aside.
In a saut pan, melt the butter over medium-high heat. Saut the onion, celery, green onion, and garlic until wilted.
Remove from heat and add the port and cognac. Return to the stove burner and ignite the cognac with a kitchen match and allow it to burn off.
Reduce the liquid to about half the volume. Mix in the thyme and black pepper. Remove from heat and allow to cool completely.
Add the cooled veggies to the ground meat. Add the parsley, salt, and cayenne. Mix well by hand.
To check the seasoning, take a small ball of the sausage and form a patty. Fry until no longer pink. Allow to cool and taste. Adjust seasonings accordingly.
Stuff into sausage casings using the sausage attachment of a meat grinder. TIP: if you don't feel like stuffing your own sausage, you local butcher will probably do it for you for a nominal fee.
Smoke the sausages at a temperature of 175F until the internal temperature is 160F. You can serve right away or vacuum pack and freeze until later and just warm up on the grill.
TIP: a standard package of casings is usually enough for 50 feet of sausage. If you have leftover casings, do not freeze them. That well weaken them and make them prone to tearing. Drain them, and repack them with sea salt and store in the refrigerator. They will last forever. Natural casings aren't expensive but I just hate to waste anything.
