01 - Place chicken thighs or breasts in the slow cooker in a single, even layer.
02 - Whisk together soy sauce, honey, rice vinegar, brown sugar, minced garlic, grated ginger, and sesame oil in a small bowl until well combined. Pour mixture evenly over the chicken.
03 - Cover and cook on low heat for 4 hours, or until chicken is tender and easily shreds with a fork.
04 - Transfer cooked chicken to a plate and set aside. Leave cooking liquid in the slow cooker.
05 - Mix cornstarch with water in a small bowl to create a slurry. Whisk into the hot cooking liquid in the slow cooker. Cover and cook on high for 10-15 minutes until sauce reaches desired thickness.
06 - Shred chicken using two forks. Return shredded meat to the slow cooker and toss thoroughly with thickened teriyaki sauce.
07 - Serve immediately, garnished with sliced green onions and toasted sesame seeds if desired.