Add the chicken, garlic, ginger, honey, soy sauce, vinegar, sesame oil and mirin to your slow cooker.Cover and cook on low for 4 hours.
Remove the chicken from the slow cooker and shred with two forks.
Pour the sauce from the slow cooker into a medium saucepan.In a small bowl whisk together water and cornstarch.
Slowly whisk the cornstarch mixture into the sauce and bring to a boil whisking constantly.Cook for 1-2 minutes or until the sauce is thickened.
Toss the shredded chicken into the sauce and stir to coat the chicken in the sauce.
Serve immediately with sesame seeds and green onions for garnish, if desired.
Notes
Freeze Friendly Instructions: Add all of the teriyaki sauce ingredients along with the raw chicken to a freezer ziplock bag and freeze it until you are ready to use it. I like to freeze 3-4 batches at a time for easy dinners. They last for 4 months in the freezer!If using bone in chicken things increase cook time to 6 hours and check for an internal temperature of 165 degrees.