Sear the Pork: In a large skillet, heat olive oil over medium-high heat. Season the pork loin with salt and black pepper. Sear the pork on all sides until browned (about 3-4 minutes per side). Remove from heat and set aside.
Prepare Aromatics: In the same skillet, add chopped onions and garlic. Sauté until the onions are translucent (about 3-4 minutes). This step adds depth to the flavor.
Combine Sauce Ingredients: In a bowl, mix together the cranberry sauce, chicken broth, thyme, rosemary, balsamic vinegar, and brown sugar (if using). Stir until well combined.
Assemble in Crockpot: Place the seared pork loin at the bottom of the crockpot. Pour the cranberry sauce mixture on top and scatter the sautéed onions and garlic over everything.
Cook: Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the pork is tender and easily pulls apart with a fork.
Shred and Serve: Once cooked, remove the pork from the crockpot and shred it with two forks. You can mix the shredded pork back into the sauce for a flavorful dish or serve it sliced with the sauce drizzled on top.
Garnish: Sprinkle with fresh chopped parsley for a pop of color and freshness before serving.