Cook rotini as pkg. directs. Rinse under cold water; drain. Cut broccoli into flowerets; cook in small amount of boiling water for 3 to 5 minutes or til crisp tender. Drain. Remove chicken from bones, cut into bite size pieces. In large bowl, mix pasta, broccoli, chicken, red pepper, ripe olives, and green onion. Toss lightly.
In a small bowl, stir together sour cream, mayonnaise, wine vinegar, cream, sugar, salt, tarragon, and pepper. Pour over pasta mixture and toss. Cover and chill. Makes 4 main dish servings.