Combining steak with salad is blasphemy to some people, but with the right flavors it can be really delicious. Since you have flank steak at the ready, this salad can be made practically on a whim.
One key to making this salad really pop is the steakhouse dressing. Take the time to try it out. It takes maybe 3 minutes to whip up and will blow any store-bought dressing out of the water.