1. Cut onion in half and thinly slice. Add to large mixing bowl.
2. Peel skin on cucumbers. Slice lengthwise and scoop out the seeds. Discard or compost. Thinly slice and add to bowl.
3. Add pot of water on stove and set to boil. Peel carrots and thinly slice them, adding to water once it has reached a boil. Fill a separate bowl with ice cubes and cold water. Once carrots have cooked in water for 5 minutes, remove from heat. Drain pot and place carrots in ice bowl. This will shock them from further cooking and retain their vibrant orange. Remove carrots from ice bowl and drain on paper towels for a few minutes or pat dry. Add carrots to bowl with onion and cucumbers.
4. Add olive oil to bowl along with pepper, salt, and garlic. Toss.
5. If you are serving immediately, continue with step 6. Otherwise, cover with plastic wrap and set aside until you are ready to serve and proceed with step 6.
6. Slice tomatoes in large chunks. Add to bowl.
7. Add wine vinegar, balsamic vinegar, and fresh basil leaves to bowl and toss all the ingredients together.
8. Taste to see if it needs any additional salt or pepper and add to your liking and serve.