Green Bean Chicken Stir-Fry

This is my version of Panda Express String Bean Chicken Stir-fry.  I have finally finished experimenting with this one.  For one reason it was hard to duplicate.  I was making it too complicated when it's really a very simple recipe with simple ingredients.  Finally, I've got it almost exactly!

Recipe:

1 C oil
1 lb chicken, cut in pieces on angle
¾ lb fresh green beans, snapped
1 medium onion, cut in thin wedges
1/2 inch piece fresh ginger, chopped fine
1 lg garlic clove, chopped fine

Marinade:
1 Tbs soy sauce
1 tsp white grape juice
1/2 tsp rice vinegar
1 Tbs cornstarch

Sauce:
1 tsp cornstarch
2-3 Tbs soy sauce (start with 2 and add more if needed while stir-frying)
3 Tbs water
1 tsp sugar
1/2 Tbs grape juice
1/2 tsp rice vinegar

Mix marinade together and add to chicken.  Let the chicken marinade for 30 minutes at least.  Mix sauce together and set aside. Heat oil in wok on high to 375°F. Fry green beans in oil in small batches for 20 seconds. Drain the beans on a rack and put aside.  Drain out all but 4-5 Tbs of the oil, heat wok on high, Add ginger, garlic and chicken and stir-fry until cooked through, adding more oil if needed. Add sauce and stir until it's thickened.  Add onions and stir-fry about 1 minute, adding a little water and soy sauce if needed.  Stir in green beans and remove from heat. Serve with rice.