Place the chicken breasts in a slow cooker.

In a small bowl, whisk together the garlic, ginger, honey, brown sugar, soy sauce, sesame oil and rice vinegar. Pour the soy sauce mixture over the chicken.

Place the lid on the slow cooker and cook on HIGH for 3-4 hours or LOW for 6-7 hours.

Remove the chicken from the slow cooker and shred with two forks.

Pour the teriyaki sauce from the slow cooker through a strainer into a saucepan. Place the saucepan on the stove over medium high heat and bring to a simmer.

In a small bowl, mix together the cornstarch and water and stir until dissolved. Pour the cornstarch into the pan and bring to a boil. Cook for 1-2 minutes or until the sauce has just thickened.

Pour the sauce over the shredded chicken and toss to coat the chicken evenly in the sauce. Sprinkle the chicken with sesame seeds and green onions, and serve.