01 - Arrange the sliced red onion and minced garlic evenly across the bottom of the slow cooker insert.
02 - Place the chicken thighs in a single layer on top of the onion and garlic mixture, ensuring even distribution for consistent cooking.
03 - In a small mixing bowl, whisk together the balsamic vinegar, honey, chicken broth, Dijon mustard, olive oil, dried basil, dried oregano, salt, and black pepper until fully incorporated and smooth.
04 - Pour the prepared balsamic sauce evenly over the chicken thighs, ensuring all pieces are well-coated.
05 - Cover the slow cooker with its lid. Cook on low setting for 6 hours or on high setting for 4 hours, until the chicken reaches an internal temperature of 165°F and is tender throughout.
06 - For a thicker sauce, carefully remove the cooked chicken and set aside. Transfer the cooking liquid to a saucepan and simmer over medium heat for 5–8 minutes until reduced and slightly thickened, then return the chicken to the sauce.
07 - Sprinkle with freshly chopped parsley just before serving. Serve hot over rice, mashed potatoes, or alongside steamed vegetables.