Cut the cauliflower into bite-sized pieces. This will allow it to cook fast since the pieces are small. Fill a saucepan with water and a pinch of salt over the stove. Once the water is boiling, add the cauliflower and boil it for 2-3 minutes. Check the cauliflower and make sure not to overcook it.
Once the cauliflower is done, carefully pour it into a strainer. Run cold water over the strainer to stop the cauliflower from cooking. Or, place the cauliflower in an ice bath.
Hard-boil the eggs. Then, slice the hard-boiled eggs into small pieces.
Wash, dry, and chop the celery. Also, dice the red onion and chop the parsley.
Add the cauliflower, hard-boiled eggs, celery, red onion, and parsley to a large bowl.
In a separate both, mix the 0-fat greek yogurt, light mayonnaise, stone-ground mustard, garlic powder, salt, and pepper.
Add the dressing to the bowl with the rest of the ingredients. Mix everything together and enjoy!