Cut the cauliflower into bite-size pieces. Place in a large microwave-safe bowl. Add a tablespoon of water, cover with a microwave-safe plate and microwave on high for 7 minutes, or until just tender. Strain into a colander and allow to cool for a few minutes. Transfer to a large serving bowl.
Stir in the celery, the pickles and the onions.
In a small bowl, mix together the mayonnaise, mustard, garlic, salt and pepper. Add to the cauliflower mixture and mix gently with a spatula.
Gently stir in the eggs. Serve immediately, or cover and chill for an hour or so to allow flavors to meld.