Fruit Soup
Fruit soups are a pleasant change during the summer season. Pick over, stem and wash one quart of sour cherries, simmer slowly in one quart of water until tender, then rub through a sieve and return to the fire. Sweeten with one-half of a cupful of sugar, and when boiling thicken slightly with one tablespoonful of arrowroot rubbed to a paste with a little cold water. As soon as the soup looks perfectly clear, take from the fire, add one teaspoonful of lemon juice and put it aside to cool. Serve it in glasses or cups with cracked ice added just as it goes to the table.
A cold cherry soup that behaves more like a loose fruit dessert than a first course. Nearly all of the technique hangs on the arrowroot, which needs a light hand and no prolonged boiling.
- Arrowroot is the hingeArrowroot thickens almost instantly and then breaks down if held at a boil, turning the soup thin and slightly slimy. Stir the slurry in, let the mixture return just to the boil until it clears, and pull it off the heat immediately. Cornstarch can be substituted, though the quantity may need adjusting, and it gives a cloudier, more opaque result, which is what this recipe appears to be trying to avoid.
- A quart of cherriesMeasured whole and unpitted, that is roughly 1 1/4 to 1 1/2 lb, or about 600-700 g. Sour cherries here means Morello or Montmorency, not sweet Bing types; if you can only find sweet cherries, cut the sugar sharply and increase the lemon juice, since the acid is what keeps the soup from tasting flat.
- Pits and the sieveThe recipe never says to pit the fruit, and simmering the cherries whole then rubbing them through a sieve leaves the pits behind. Do not crush or grind the pits to extract flavour, and do not extend the simmer far beyond tenderness; the kernels contain amygdalin. Pitting first, if you prefer, costs nothing but time.
- Rubbing through a sieveA fine-mesh sieve and a stiff rubber spatula or the back of a ladle will do it. A food mill fitted with the medium plate is faster and holds back skins and pits cleanly. Avoid a blender, which pulverises skins and clouds the finished soup.
- SweeteningHalf a cupful is about 100 g, which is modest for genuinely sour cherries. Taste after sieving and adjust before you add the arrowroot, since sugar dissolved into a thickened soup takes longer to disappear.
- Chilling and the iceCover the surface while it cools to keep a skin from forming, then refrigerate until thoroughly cold rather than relying on the cracked ice to do the work. The ice is added at the table for effect and to keep the glass cold; too much of it waters the soup down.
- YieldAbout 5 cups finished, serving four to six in glasses or teacups as the recipe intends. A spoonful of sour cream or unsweetened whipped cream floated on top is a traditional accompaniment in the Central European versions of this dish and cuts the sweetness.
Cold fruit soups came into American cookbooks by way of Central and Northern European kitchens, where they are a summer fixture rather than a novelty: the German Kaltschale and Kirschsuppe, Danish kirsebærsuppe, Hungarian meggyleves, and their Polish and Scandinavian relatives all work on the same principle of stewed sour fruit, sugar, a light starch bind and an acid finish. The framing here, that fruit soups are "a pleasant change," may suggest the dish was not simply assumed to be familiar to American readers. Sour cherries suited the purpose because they are sharp enough to want sweetening. Arrowroot sets clear where flour and cornstarch set cloudy, so a translucent ruby soup served in glassware was presumably part of the appeal.