Heat 2 tablespoons of olive oil in a large pan over medium high heat.
Season the pork loin generously on all sides with the salt, pepper and Italian seasoning.
Place the pork in the pan. Cook for 5-6 minutes per side, or until deep golden brown.
Place the pork in a slow cooker. I recommend using a 6 quart pot. If you have a smaller crock pot, you can cut the roast into segments to fit into the pot.
In a medium bowl, mix together the last tablespoon of olive oil, chicken broth, soy sauce, balsamic vinegar, brown sugar and minced garlic.
Pour the chicken broth mixture over the pork. Cover the crock pot and cook on low for 6-8 hours, or high for 4 hours.
Remove the pork from the crock pot. Place the meat on a plate and cover to keep warm.
Pour the liquid from the slow cooker into a small pot. Place the pot on the stove over medium heat and bring the sauce to a simmer.
Mix the cornstarch with 1/4 cup of cold water. Add the cornstarch mixture to the pot and bring to a boil.
Cook for 1 minute, or until sauce has started to thicken.
Add the butter to the pot and stir until it has melted. Take the pot off the heat.
Slice or shred the cooked pork and drizzle the sauce over the top. Sprinkle with parsley and serve immediately.