01 - Place chicken thighs in an even layer at the bottom of the slow cooker insert.
02 - Whisk together soy sauce, honey, ketchup, rice vinegar, sesame oil, garlic, ginger, and red pepper flakes in a medium bowl until fully combined.
03 - Pour the sauce mixture evenly over the chicken. Cover and cook on low setting for 4 hours until chicken is tender and reaches internal temperature of 165°F.
04 - Transfer cooked chicken to a cutting board. Shred using two forks or cut into bite-sized pieces.
05 - Whisk cornstarch and water in a small bowl until smooth. Stir into the sauce remaining in the slow cooker.
06 - Return shredded chicken to the slow cooker. Stir well to coat. Cover and cook on high for 15-20 minutes until sauce has thickened to desired consistency.
07 - Spoon chicken and sauce over steamed rice. Garnish with sesame seeds and sliced green onions.