Place the tortilla on a flat surface and spread the mayonnaise as a thin layer on top. Place the lettuce leaves in the middle of the tortilla. Grate a carrot, or use carrot sticks, and place it on top of the lettuce along with the corn kernels. Lay the roast beef slices on top of the vegetables to hold them in place.
Fold the sides in, and one end over the filling, rolling the wrap tightly as you tuck the sides in. Slice in half.
Pack it for lunch:
Place the wrap inside the main compartment of a lunchbox. Add healthy sides, like fresh fruit and veggies in separate compartments to complete the lunch.
Cover with the lid and refrigerate until ready to pack inside a lunch bag with or without an ice pack.