Arrange chicken thighs in an even layer in the slow cooker crock.
Combine soy sauce, honey, rice vinegar, sesame oil, ginger, and garlic in a mixing bowl until homogenized.
Pour the liquid mixture over the chicken.
Secure the lid and cook on the low setting for 4 hours.
Transfer chicken to a clean surface and cut into 1-inch pieces.
Whisk cornstarch and cold water to form a smooth slurry.
Incorporate the slurry into the slow cooker liquid.
Set slow cooker to high for 15 minutes to allow the sauce to achieve a thick viscosity.
Fold the chicken back into the sauce to coat.
Garnish with sesame seeds and green onions before service.