Salt and pepper.
Soak the cauliflower head downward in salted water, and then cook it until tender. Remove some of the best flowers to serve in the soup, and press the rest through a sieve. Add the water if it is not too strong.
Scald a slice of onion in twice the quantity of milk that you have of pulp. Add the pulp to the milk and onion, season with salt and pepper, and lastly add the flowerlets of the cauliflower.