Preheat the grill to medium. Remove the outer layers of the corn husks and then soak the whole cob in water for about 30 minutes. Peel back remaining husks and remove hair. Brush the kernels with olive oil; then pull husks back over the ear. Place the cobs on the grill and cook for about 15 minutes.
Once the cobs have cooled, cut kernels off the cob.
Add tomatoes, onion and basil to corn.
Combine oil, vinegar, sugar, salt and pepper; mix well.