In a mixing bowl, whisk together soy sauce, honey, brown sugar, sesame oil, rice vinegar, minced garlic, fresh ginger, and red pepper flakes until smooth.

Place the chicken strips into the slow cooker. Pour the teriyaki sauce over the chicken and stir gently.

Cover the slow cooker and cook on HIGH for 3 hours or LOW for 5-6 hours, until chicken is fork-tender.

Remove the chicken, shred it into bite-sized pieces, and set aside.

Combine cornstarch with water to make a slurry. Whisk until smooth.

Strain the cooking liquid into a saucepan and bring to a gentle simmer.

Whisk in the cornstarch slurry and cook until sauce thickens.

Return shredded chicken to the sauce and stir to coat.

Serve garnished with sesame seeds and green onions.