01 - Place boneless, skinless chicken thighs or breasts in the bottom of the slow cooker, ensuring even distribution for consistent cooking.
02 - Whisk together pineapple juice, low-sodium soy sauce, brown sugar, ketchup, rice vinegar, minced garlic, and grated fresh ginger in a medium bowl until sugar dissolves completely.
03 - Pour the prepared sauce evenly over the chicken pieces, ensuring all meat is coated for maximum flavor absorption.
04 - Layer sliced onion, red and yellow bell pepper pieces, and pineapple chunks over the chicken and sauce mixture.
05 - Cover and cook on LOW setting for 4-5 hours until chicken reaches internal temperature of 165°F and becomes tender enough to shred easily.
06 - Remove cooked chicken and vegetables to a serving platter using a slotted spoon, cover loosely with foil to maintain warmth.
07 - Mix cornstarch and water in a small bowl until smooth, ensuring no lumps remain for even thickening.
08 - Transfer cooking liquid from slow cooker to a saucepan, bring to simmer over medium heat, whisk in cornstarch slurry gradually, and cook 2-3 minutes until sauce reaches desired consistency.
09 - Pour thickened sauce over chicken and vegetables, garnish with sliced green onions and sesame seeds, serve immediately with steamed rice.