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