Cook and cool the cauliflower. Bring a large pot of water to a boil, then add the cauliflower. Cook for about 10 minutes, stopping when the florets are tender but still firm. Drain the cauliflower, rinse it under cold water to cool it, then drain it completely.
Blend the dressing. While the cauliflower is being prepared, place all of the dressing ingredients in a blender. Blend until the mixture is smooth.
Combine the salad. Put the cauliflower into a large bowl with the chopped eggs, celery, green onion, shallot, and dill. Pour in the dressing and mix until everything is thoroughly combined.
Chill before serving. Transfer the finished salad to the refrigerator and leave it there until chilled.