In a small bowl whisk together the dressing ingredients. Set aside.
Cut cauliflower into bite-size florets and place them in a pot with approximately 1 inch of water. Place lid on the pot and bring to a boil steaming the cauliflower for 3-5 minutes until it is slightly tender.
Drain the cauliflower and pat dry. Place in a gallon size resealable bag, or a resealable container and pour half of the dressing over it. Place in refrigerator to marinate for at least 1 hour or overnight.
Next day toss all ingredients together and pour remaining dressing over the antipasto salad.