1In medium bowl, mix mayonnaise, sour cream and dressing until smooth. Refrigerate at least 30 minutes to blend flavors. Garnish with chives.
2Meanwhile, heat oven to 450°F. In large bowl, toss vegetables with oil and seasoned salt to coat evenly. Arrange vegetables in ungreased large shallow roasting pan, at least 16x12 inches.
3Bake 15 to 20 minutes or until crisp-tender. Refrigerate vegetables at least 8 hours or overnight, and serve cold with dip.