Mongolian Beef and Bok Choy

3 cups flank steaks, thinly sliced against the grain
1 cup shiitake mushrooms, thinly sliced
1 cup bok choy
1 tablespoon oyster sauce
1/2 cup vegetable oil
1/8 cup fresh ginger
2 cloves finely chopped garlic
1/2 tablespoon sesame oil
1/4 cup light soy sauce
1/3 cup chicken broth

Marinate the flank steak in the oyster sauce and 1/4 cup vegetable oil.
In a separate bowl mix soy sauce, sesame oil, and chicken broth. Sauté garlic and ginger in very hot wok. Add flank steak and sauté for 2 minutes. Add bok choy and sauté for 2 minutes. Add sauce and cook for 30 seconds.