1 1/2 lbs fresh broccoli  | 
                                                1 tablespoon wine vinegar  | 
                                                2 teaspoons dijon mustard  | 
                                                1 tablespoon capers, drained  | 
                                                1/8 teaspoon sugar  | 
                                                1 tablespoon chopped fresh tarragon  | 
                                                2 tablespoons finely chopped scallions  | 
                                                2 tablespoons mayonnaise  | 
                                                1/3 cup sour cream  | 
                                                2 tablespoons chopped chives  |