Dice bell peppers and cucumber and add to a large bowl. Slice scallion whites and greens and add them to the bowl.
Grate the carrots and add them, then add 2 cups of corn. Toss all veggies together gently.
If you plan to serve immediately, add the dressing and toss until coated. To keep fresher longer, store the veggies in an airated container and store the dressing separately.