1. Put tomatoes, onion, olive oil, vinegar, garlic, salt, pepper and oregano in a large bowl; toss. Let stand at room temperature at least 30 minutes or until tomatoes release their juices, tossing occasionally.
2. Cook pasta as package directs. Drain and add to bowl with tomatoes; lightly toss. Let come to room temperature. Add basil; toss. Serve or refrigerate up to 1 day.