01 - Whisk together pineapple juice, soy sauce, ketchup, brown sugar, rice vinegar, ginger, garlic, sesame oil, and black pepper in a medium bowl until fully combined and sugar dissolves.
02 - Place chicken thighs in the crock pot, arranging them in an even layer. Pour the prepared marinade sauce over the chicken, ensuring all pieces are thoroughly coated.
03 - Cover and cook on low setting for 4–6 hours until chicken is cooked through, tender, and reaches an internal temperature of 165°F.
04 - Transfer cooked chicken to a serving platter and tent with foil. Whisk cornstarch with water in a small bowl to create a slurry. Stir slurry into the sauce in the crock pot, cover, and cook on high for 10–15 minutes until sauce thickens. Return chicken to pot and coat evenly.
05 - Plate chicken over steamed rice, spooning extra sauce on top. Sprinkle with sliced green onions and toasted sesame seeds. Add fresh pineapple slices alongside for a tropical presentation.