Whisk soy sauce, oyster sauce, chicken broth, and cornstarch in a small bowl to create the sauce.
Heat vegetable oil in a large wok or skillet over high heat.
Add chicken strips and stir-fry until cooked through, approximately 5-6 minutes. Remove chicken from pan.
Add green beans to the pan with a splash of water, cover, and steam for 2 minutes until bright green and crisp-tender.
Add garlic, ginger, and red pepper flakes to the pan; sauté for 30 seconds until fragrant.
Return chicken to the pan and pour in the sauce mixture.
Stir-fry for 1-2 minutes until the sauce thickens and coats the chicken and beans.
Drizzle with sesame oil and serve immediately.