Grill the corn on the cob until slightly charred all over. When cool enough to handle, slice the kernels off the cob. Add to a mixing bowl along with the tomatoes and red onion.
Meanwhile, bake the garlic toast according to package directions. Cut into one-inch cubes and add to the mixing bowl.
In a small bowl or mason jar, combine the oil, vinegar, and pepper. Whisk or shake until fully combined. Pour the dressing over the salad. Add the fresh basil and toss gently. Serve immediately or refrigerate 2-4 hours to allow flavors to blend. This salad is best eaten the same day.