Stir the cornstarch and water together in a small bowl until combined, then pour into a medium saucepan over low-medium heat. Add the brown sugar, honey, soy sauce, vinegar, garlic, and ginger. Allow to simmer while whisking occasionally. Bring to a boil and allow to boil for 1 minute, then remove from heat.

Place chopped onion and chicken into a 4 quart or larger slow cooker. (Here’s one I own and love!) Pour teriyaki sauce on top. Cook on high for 3 hours or on low for 5 hours.

Remove the chicken from the slow cooker and, using 2 forks, shred into smaller pieces. Place back into the slow cooker and stir to combine. Cook for 1 more hour on low, stirring occasionally.

Garnish with sesame seeds and scallion, if desired, and serve on top of cooked rice or quinoa or alongside steamed vegetables. Or pile onto rolls and enjoy sandwich style. Keep leftovers in a large tupperware in the refrigerator for up to a week. Reheat in the microwave.