01 - Place the chicken thighs or breasts in the bottom of the slow cooker, ensuring even distribution for consistent cooking.
02 - In a medium bowl, whisk together pineapple juice, soy sauce, brown sugar, ketchup, rice vinegar, minced garlic, and grated ginger until sugar dissolves completely.
03 - Pour the prepared sauce evenly over the chicken in the slow cooker.
04 - Layer the sliced onions, bell pepper pieces, and pineapple chunks over the sauced chicken.
05 - Cover and cook on LOW setting for 4 to 5 hours, or until chicken reaches internal temperature of 165°F and is fork-tender.
06 - Transfer the cooked chicken and vegetables to a serving platter; cover loosely with foil to maintain warmth.
07 - In a small bowl, mix cornstarch and water until smooth and no lumps remain.
08 - Pour the cooking liquid from the slow cooker into a saucepan. Bring to a simmer over medium heat, whisk in the cornstarch slurry, and cook for 2 to 3 minutes until sauce thickens and coats the back of a spoon.
09 - Pour the thickened sauce over the chicken and vegetables. Garnish with sliced green onions and sesame seeds. Serve immediately over steamed rice.