In medium bowl, combine all dip ingredients except sun-dried tomatoes; beat until smooth and creamy. Fold in tomatoes. Cover; refrigerate 1 to 2 hours to blend flavors.
In Dutch oven, bring about 4 quarts (16 cups) water to a boil. Add broccoli and cauliflower; cook 30 seconds. Drain; rinse with cold water. Cover; refrigerate 1 hour or until cool.
Drain broccoli and cauliflower again. Arrange in ring on large serving platter to form wreath shape, alternating stripes of broccoli and cauliflower. Decorate with red bell peppers cut into stars or long strips.