Add 1/3 cup honey, 1/4 cup apple cider vinegar, and 1 tablespoon soy sauce to a small bowl and mix until well blended.
Season the pork loin with coarse sea salt, pepper, garlic powder, and paprika on all sides. Rub the spices into the meat to ensure even coverage.
Place the seasoned pork loin in a vacuum-seal bag, reusable sous vide bag, or a resealable zipper-lock bag. Pour 1/4 cup of the honey marinade into the bag with the pork. Seal the bag (see recipe notes). Store the remaining honey marinade in the fridge for the sauce after the pork is cooked.
Preheat your sous vide water bath with the sous vide cooker to 130-150°F, depending on your desired doneness. Submerge the sealed bag in the water bath and cook for the appropriate time (see recipe notes).
Once the pork loin is done cooking in the sous vide bath, remove it from the bag and pat it dry with paper towels. Do not discard the liquid in the bag.
Heat a cast-iron skillet or sturdy frying pan over medium/high heat for several minutes. Add several tablespoons of light olive oil and sear the pork loin for 1-2 minutes on each side until golden brown.Transfer the seared pork loin to a cutting board and let it rest for 5 minutes to retain its juices. Slice the pork into 1/2-inch thick pieces. Add 3 tablespoons of the pork liquid from the sous vide bag to a small bowl with 1-1/2 tablespoons of cornstarch. Gently stir until dissolved to make a slurry.
In a small saucepan over medium heat, add 1/4 cup butter, 4 minced garlic cloves, and 1/2 teaspoon of Italian seasoning. Cook for several minutes until the garlic is soft and fragrant. Pour in the remaining marinade, the dissolved cornstarch slurry, and 1/4 cup of the pork liquid. Bring the mixture to a simmer and cook for 3-4 minutes, allowing the flavors to meld. Adjust the thickness by stirring in more of the pork bag liquid if needed.Drizzle the honey garlic sauce generously over the sliced pork loin and serve.