Serve ranch dressing dip alongside blanched green bean and -- stems and -- or with thin carrot and celery sticks arranged with radish rounds to look like flowers and stems.
Blanch beans: Prepare an ice bath; set aside. Bring 6 quarts water to a boil in a large saucepan; season with salt. Place green beans in boiling water, and blanch until bright green and just cooked, 4 to 5 minutes. Using tongs or a slotted spoon, transfer beans to ice bath. When cool, 3 to 5 minutes, remove and drain; set aside.
In a small bowl, combine mayonnaise and mustard; set aside. Work in assembly-line fashion, making open-face sandwiches before cutting into shapes: Spread mayonnaise mixture on a slice of bread. Top with sandwich meat or cheese. Use 2- and 3-inch flower cookie cutters to cut shapes from the sandwiches, avoiding crusts. Save scraps as snacks.
To make flower centers, top with a sliced olive, half a cherry tomato, or an extra piece of cheese or sandwich meat cut with a smaller flower cutter, about 2 inches in size. Arrange sandwiches as desired for serving, using green beans to make stems. Serve immediately with dip, or cover with plastic wrap, and store in the refrigerator until ready to serve.