Look for flank steak that has a clear, red color. Beef normally is purplish-red, but when exposed to oxygen it takes on a cherry-red hue known as the “bloom.” While the exterior is bright red, the interior of the meat retains the darker color. Vacuum-packed flank steak also shows this purplish color. Packaged flank steak should be cold and the packaging free of punctures or tears; vacuum-packed flank steak should have its seal intact. The beef should be firm to the touch. Check the label for the “sell-by” date and make sure to buy it before or on that date.