Zigzag piping gives these airy meringues a fresh look.
Preheat oven to 200 degrees. Put egg whites and cream of tartar into the bowl of an electric mixer fitted with the whisk attachment; beat on medium speed until frothy. With mixer running, gradually beat in sugar until foamy and opaque. Raise speed to high. Beat until stiff (but not dry) peaks form. Reduce speed to low, and beat in food coloring, 1 drop at a time, until desired shade.
Transfer meringue to a pastry bag fitted with a 3/4-inch petal tip (such as Ateco #118). Using a back-and-forth motion, pipe 1 1/2-inch vertical accordions onto baking sheets lined with parchment, spacing about 1 1/2 inches apart. Bake 1 1/2 hours. Turn off oven, and let meringues stand in oven until dry, about 1 1/2 hours more. Meringues can be stored in single layers in airtight containers up to 1 week.