Place steak on rack in broiling pan and broil, turning once, until rare, about 5 minutes on each side.
Slice steak diagonally across the grain and cut each strip in half lengthwise; set aside.
In 12-inch nonstick skillet heat oil; add garlic and ginger and saute until garlic is browned (be careful not to burn).
Remove and discard garlic and ginger.
Add vegetables to skillet and saute, stirring constantly, until tender-crisp.
In 2-cup measure or small bowl combine broth, sherry, oyster sauce, and cornstarch, stirring to dissolve cornstarch; add to vegetables and, stirring constantly, bring to a boil.
Reduce heat, stir in steak slices, and let simmer until mixture is thoroughly heated.