In a bowl, whisk together all the ingredients for the sauce.
In the slow cooker, add the chicken, onions and cover with the sauce.
Cook on low for about 6 hours or until chicken completely cooked.
After the 6 hours remove the chicken and shred it. To a saucepan over med heat, pour in the liquid from the slow cooker and add in the cornstarch slurry. Once combined, add the shredded chicken to the sauce pan and mix well.