Combine the chicken, soy sauce and rice wine vinegar in a large zip-top bag, and toss until the chicken is evenly coated. Refrigerate for at least 30 minutes, or up to 8 hours. (If no time to marinate, just toss the chicken, soy sauce and vinegar in a small bowl and let sit while you prep the rest of the recipe).
In a small bowl, whisk the sauce ingredients together until combined (cornstarch should no longer be visible). Set aside.
Heat a tablespoon of oil in a large skillet over medium-high heat. Add green beans and season with a pinch of salt. Stir and cook for 3-4 minutes, until beans are bright green but still crisp. Transfer to a large plate or bowl and set aside.
Add another tablespoon of oil to the skillet over medium-high heat. Pour the chicken from the bag into the hot skillet. Season the chicken with a pinch of salt and pepper.
Add the chicken and saute for 5-7 minutes or until cooked through and no longer pink, stirring and turning the chicken occasionally for even browning. Using a slotted spoon, add the chicken to the plate with the green beans.
Pour the whisked honey lemon sauce into the empty saute pan. Cook over medium-high heat for 2-3 minutes, or until the sauce reaches a low boil and thickens. Taste and adjust seasonings to your liking (salt, pepper, honey, lemon).
Add the chicken and green beans back into the pan and toss until evenly coated with the sauce. Remove from heat and serve immediately, topped with green onions and sesame seeds, if desired.
Can be served over steamed white or brown rice, or on its own.