Cream of Watercress

A basic bechamel with cress folded in, scaled for a camp stove or a home range. The only real decisions are how long to cook the cress and how hard to push the finished soup.

• Cook the cress far lessTen minutes in boiling water turns watercress olive-drab and flattens its pepper. Two to three minutes is enough to soften the stems; blanch, then puree with the cooking liquid if you want a smooth soup.
• Keep the cooking waterThe recipe has you cook the cress in a cup of boiling water and does not say to drain it. Stir it in along with the cress; colour and flavour carry over into that liquid, and it also loosens the finished soup.
• White sauce proportionsThree tablespoons each of butter and flour to three cups milk works out to one tablespoon per cup, a thin white sauce by the usual reckoning. Cook the roux a minute or two before adding milk so it does not taste raw, and add the milk gradually off the heat to avoid lumps.
• Do not actually boil it"Bringing to boiling point" with cream in the pot risks curdling. Heat until steam rises and the surface just trembles, then serve.
• Evaporated milkThe book offers it as an equal substitute for cream, without comment. Modern evaporated milk works the same way but is thinner than heavy cream and carries a faint cooked sweetness; do not reach for sweetened condensed by mistake.
• SeasoningOne teaspoon salt for four and a half cups of liquid is modest. Taste at the end, and add pepper generously; watercress and white pepper suit each other, and a scrape of nutmeg is a common addition to bechamel.
• YieldAbout four and a half cups, or four servings as a first course. It thickens as it stands; loosen with milk or the reserved cress water when reheating.