In a large measuring cup or bowl add the soy sauce, chicken broth, cornstarch, mirin, sugar, sesame oil and white pepper and whisk until everything is completely dissolved.
In a large skillet add one teaspoon canola oil on medium high heat and cook half the chicken until just cooked through, about 2-3 minutes on each side.
Repeat with the second half of the chicken and an additional teaspoon of oil.
Remove the chicken to a plate.
Add in the remaining oil, garlic and ginger and cook for 30-45 seconds until very fragrant but not browned.
Stir the garlic and ginger well and add in the sauce, whisking well.
Add in the green beans and let the sauce cook for 2-3 minutes until thickened.
Add in the chicken and stir well to coat.
Garnish with sesame seeds if desired.