Cook pasta according to package directions; drain and rinse with cold water. Place in a large serving bowl. Stir in the onion, tomato, cucumber, green pepper and parsley; set aside. In a small saucepan, combine the dressing ingredients. Cook over medium-low heat for 10 minutes or until sugar is dissolved. Pour over salad and toss to coat. Cover and refrigerate for 2 hours. Serve with a slotted spoon.