Potage de Santé

Ingredients

Equipment Needed

• •5-quart (4.7 L) heavy saucepan
• •2-quart (1.9 L) saucepan
• •Sturdy fine-mesh metal sieve
• •Flexible bowl scraper
• •Whisk
• •Instant-read thermometer, optional

Instructions

1. 1

   Boil the potatoes

   Bring the water and salt to a brisk boil in a heavy saucepan. Add the quartered potatoes, return the water quickly to the boil, and cook uncovered at a steady pace for 15 to 18 minutes. They're ready when a knife passes through the centre without resistance and the corners begin to soften, but before the pieces collapse into the water. Drain thoroughly and leave them in the hot colander for 2 minutes so excess moisture escapes.

2. 2

   Sieve while hot

   Set a sturdy fine-mesh sieve over the cleaned saucepan and press the hot potatoes through with a flexible scraper. Work in small amounts, scraping the underside of the sieve as the fine purée gathers there. Don't use a food processor or immersion blender; fast blades overwork potato starch and turn this delicate soup elastic. If the potatoes cool and resist the sieve, warm them gently over a pan of hot water before continuing.

   The fine sieve is not brigade ornament. It gives the potage its particular silk and removes every stubborn fragment without beating the potato into paste.
3. 3

   Dilute with consommé

   Warm the white consommé in the second saucepan. Whisk one cup into the potato purée until completely smooth, then add the remainder in several additions. This gradual dilution prevents small lumps from escaping into the finished soup. Bring it to a bare simmer for 4 to 5 minutes, stirring along the bottom. It should pour like light cream and coat a spoon thinly; if it seems loose, correct it now with another minute of gentle simmering, because reducing after the liaison is added risks curdling it.

4. 4

   Melt the sorrel

   Melt the tablespoon of butter in the emptied consommé saucepan over medium-low heat. Add the shredded sorrel and turn it through the butter for 2 to 3 minutes, until it collapses into a soft, dark green tangle and its raw sharpness mellows. It will lose its bright colour. This looks alarming and is exactly right. Fold the buttered sorrel through the simmering potato base, then lower the heat.

5. 5

   Temper the liaison

   Whisk the egg yolks and ¾ cup cream together in a heatproof bowl. Remove the soup from the heat, then whisk about 1 cup of it into the liaison in a thin stream. Pour the tempered liaison back into the saucepan while whisking constantly. Return the pan to the lowest heat and stir for 2 to 3 minutes, until the soup reaches about 165°F (74°C), gains a little body, and shows no bubbles. If fine grains appear, lift the pan off the heat at once and whisk in the 2 tablespoons of cold rescue cream. Ça se rattrape: pass the soup through a clean fine sieve and do not return it to the boil.

   A full boil scrambles the liaison. Keep the whisk moving, watch the surface rather than the clock, and remove the pan before the first bubble rises.
6. 6

   Monter au beurre

   Keep the saucepan off the heat. Monter au beurre, finish by whisking in the cold butter, one cube at a time, letting each disappear before adding the next. The finished surface should look smooth and carry a quiet butter sheen, never an oily slick. Taste before adding more salt, since a properly seasoned white consommé may have supplied all the soup needs. If the potage has tightened too far, loosen it with a tablespoon of hot water at a time.

7. 7

   Garnish and serve

   Ladle the potage into warm soup plates. Float three very thin French soup-flute roundels on each serving and scatter over the chervil pluches. Serve immediately while the bread remains crisp and the liaison is at its silkiest. À table!

Chef Tips

• •Choose a floury potato such as Bintje, Maris Piper, or russet. A waxy potato fights the sieve and gives less body, while a floury one breaks down willingly and drinks in the consommé.
• •Sorrel is the dish's tart backbone, not a decorative herb. Plain frozen sorrel is an honest out-of-season choice; thaw it, squeeze it gently, and use the same weight. Spinach with lemon makes a pleasant soup, but it isn't Potage de Santé.
• •The source assumes white consommé waiting beside the stove. Prepared chicken consommé is ideal, but a pale, carefully strained, low-salt chicken stock is the honest home equivalent because the potato makes glasslike clarity invisible. Dark roasted stock changes both the colour and the intent.
• •A French soup-flute is a long, slender crisp roll. A slim day-old ficelle serves well at home and gives the very thin roundels this garnish requires.
• •If pouring wine, choose a light, dry white with enough acidity for the sorrel, such as Muscadet or Bourgogne Aligoté. The soup needs freshness beside it, not oak.

Advance Preparation

• •The white consommé can be prepared up to 3 days ahead and kept cold, or frozen for up to 3 months. Bring it to a simmer before diluting the potato.
• •The soup can be completed through the buttered sorrel up to 1 day ahead. Cool it promptly, cover, and refrigerate; reheat it only to a bare simmer before tempering in the liaison and finishing with butter.
• •Slice the French soup-flute up to 1 day ahead and keep the roundels airtight. Pick the chervil pluches a few hours ahead, wrap them in a barely damp towel, and refrigerate.

Frequently Asked Questions

Nutrition Information

1 serving (about 265g)