Remove the casings from the fresh (raw) bratwurst sausage and discard the casing.
In a skillet sauté the bratwurst sausage in the vegetable oil over medium-high heat.
Remove the sausage once it’s browned and reserve the oil in the pan.
Add the diced apple, raisins, and chopped walnuts into the same skillet and sauté a couple of minutes. Add the butter and cook until the apples are softened.
Return the sausage to the skillet along with the Panko breadcrumbs. Stir for about 30 seconds.
Add the apple juice. Adjust the juice amount, as needed, so the stuffing mixture is not too thick or not too runny.
Add the rub to your desired taste.
Chill the stuffing for an hour before proceeding to the next step.
Fillet (butterfly) the pork loin so you end up with a flat piece. Trim off excess ridges and thicknesses to create an even piece of pork. Cover with plastic wrap and pound flat with the smooth side of a mallet. Trim the sides to square up if necessary.
Apply some rub or salt and pepper over all the flattened pork.
Evenly spread the chilled apple and walnut stuffing over the pork leaving a 1-inch (2 ½ cm) border.
Roll the pork into a spiral log then tie it with the butcher’s twine to create a log.Tip: Make sure the fat cap is on the outside of the roll to protect it while cooking and create a more balanced stuffing.
Apply some Slap Yo’ Daddy rub on the outside of the pork roll then wrap it in plastic wrap. Chill until ready to cook.
Light the smoker and set the temperature to 250 degrees F (120 degrees C). Add one large chunk of apple wood.
Place the cold stuffed pork loin into the hot pit. Cook until the pork's internal temperature is 145 degrees F (62 degrees C). About 2 hours.Tip: Placing cold meat in a hot smoker helps develop a better smoke ring.
Remove the stuffed pork loin from the pit and loosely tent with foil for 15 minutes to allow it to rest and for juices torn-distribute.
Gently heat the butter and brown sugar in a frypan. Add the Karo syrup and apple juice then simmer to reduce the mixture to the consistency of thin gravy.
Pour the glaze over the loin.
The glaze can be set by returning the stuffed pork loin to the smoker for 5 minutes.