Purée de Choux-fleurs, otherwise Dubarry

Purée de Choux-fleurs Dubarry (cauliflower purée soup) teaches the discipline of keeping pale ingredients pale. The cauliflower must taste unmistakably of itself, softened without browning, while potato gives the milk enough body to carry it. Scorched milk or browned cauliflower muddies the whole bowl, so gentle heat is the one true thing to understand before you touch the pan.

The original formula assumed a saucier with boiled milk ready, a tammy stretched beside the stove, and another pair of hands to fry the bread while the soup was skimmed. It calls for neither stock nor salamander. At home, one saucepan, a sturdy fine-mesh sieve, and a skillet do the work. I have kept its pound of cauliflower, two medium potatoes, and first pint of milk, then fixed the unspecified finishing milk and butter so you can make about two quarts without guessing. Service holding is brigade scaffolding and goes. Parboiling, the gentle milk simmer, potato binding, sieving, skimming, and butter finish stay, because they are the dish.

Finished correctly, Dubarry is ivory and softly glossy, substantial enough to coat a spoon but never heavy. The white florets tell you what it is, and the croûtons bring butter and crisp edges to each spoonful. Watch the milk simmer closely and never scrape a pan that has caught. One cook, one stove, one evening.