Place cauliflower in a large microwave-safe bowl, and pour 1/3 cup water over it. Cover and microwave until soft, 6 to 8 minutes. Once the bowl is cool enough to handle, drain any excess water, if needed.
Put 2 cups cauliflower in a blender or food processor and set the rest aside. Add the mayonnaise, sour cream, Dijon mustard, ranch dressing or dip mix, non-dairy creamer, and 1/4 teaspoon salt. Puree or pulse until blended. Don't worry if the puree isn't completely smooth. Set aside.
To the bowl with the remaining chopped cauliflower, add the onion, celery, egg whites, chives, dill, 2 tablespoons parsley, and rice vinegar. Add the pureed mixture and lightly stir to coat.
Chill for several hours before serving. Garnish with paprika and additional parsley, if using. Mmmmm!
Alternatively, prepare cauliflower on the stove in a metal steamer pot.