Add lemon juice, soy sauce, chicken broth, honey, sesame seed oil, and cornstarch to a medium bowl. Whisk until well combined, then set aside.
Heat 2 tablespoons of butter over medium-high heat in a large skillet. Add green beans to the skillet. Cook 4-5 minutes, or until beans are tender. Remove, place on a plate, and cover.
Add the remaining butter and melt. Season the chicken with black pepper, salt, red pepper flakes, and onion powder. Then, add it to the skillet and cook for 6-7 minutes, stirring occasionally, until all sides are browned.
Add garlic to the pan and saute for 30 seconds. Then, add vegetables back into the skillet, stirring occasionally.
Lower heat to medium and pour stir-fry sauce over chicken and green beans, stirring occasionally until sauce thickens.
Serve while hot over rice. Garnish with green onions and sesame seeds. Enjoy!