Oyster sauce is a thick, brown sauce made from oysters, salt and starch. If oyster sauce isn't available, you can substitute 1 tablespoon soy sauce for the 2 tablespoons oyster sauce.
This stir-fry has a lean look. The veggies are cooked in fat-free chicken broth so you get lots of flavor and fiber but no fat.
Instead of plain button mushrooms, think a little more exotic for this stir-fry. Try shiitake, cremini or brown mushrooms for a different look.