Place chicken thighs in a 5-6 quart slow cooker.
In a bowl, whisk soy sauce, honey, ketchup, garlic, ginger, sesame oil, and pepper flakes.
Pour sauce over chicken. Cover and cook on low 3–5 hours or high 2–3 hours.
Remove chicken, shred with two forks.
Mix cornstarch with water, stir into sauce, return chicken, and cook 15–20 minutes.
Top with sesame seeds and green onions. Serve over rice or noodles.
