Make the Sesame sauce by whisking together the corn starch with the rice vinegar in a small bowl. Whisk in the rest of the ingredients and set aside.
For the chicken, heat oil on medium heat and add chicken. Cook for about 5 minutes. Pour chicken in a bowl and set aside.
Add soy sauce and minced garlic (and leftover oil if there is any) to the skillet. Add Stir Fry medley and cook for a few minutes, stirring constantly.
Add the chicken back to the pan along with the stir fry sauce. Cook on medium heat until the sauce thickens (about 4-5 minutes) stirring constantly. Add salt and pepper if needed.