Place the chicken thighs in the bottom of a greased slow cooker.
In a mixing bowl, whisk together soy sauce, bourbon, vinegar, ketchup, honey, brown sugar, ginger, garlic, and red pepper flakes.
Pour the sauce over the chicken.
Cover and cook on LOW for 5–6 hours or on HIGH for 2–3 hours, until the chicken is cooked through and tender.
Remove the chicken from the slow cooker and shred or cut into chunks.
In a small bowl, whisk together the cornstarch and water until smooth. Stir into the sauce in the slow cooker.
Return the chicken to the slow cooker, stir to combine, and cook uncovered on HIGH for 15 minutes until the sauce thickens.
Serve hot, garnished with green onions and sesame seeds if desired.