1 head cauliflower
1 bunch broccoli
1 lg. red onion
1/4 c. mayonnaise
1 tbsp. vinegar
1 tbsp. sugar
1 pkg. buttermilk dressing mix

Separate cauliflower and broccoli into small flowerettes. Slice and quarter onion and toss all together. Mix remaining ingredients and pour over vegetables. Toss lightly. Cover and refrigerate overnight.