Whisk all of the dressing ingredients together, and refrigerate until ready to use. Dressing will keep for a week or more, covered, in the refrigerator.
Place the corn in a mixing bowl.
Chop the cucumber into pieces that are roughly the same size as the corn kernels, and add to bowl.
Stir in the avocado, tomatoes, and basil.
Drizzle with about 1/4 cup of the ranch dressing, and toss gently to incorporate. Check for seasoning, adding salt and pepper to taste. I usually add between 1/4-1/2 teaspoon of salt and about 1/4 teaspoon of pepper, depending on exactly how much salad I have made.
Add more dressing, if desired, or serve with additional dressing on the side.
