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Potato and Milk Soup
Wash, peel, and slice one pound of potatoes; wash and clean half a stick of celery and a leek; peel an onion, and cut all into small pieces. Put an ounce of butter or dripping into a stewpan, add the vegetables, and let them steam over the fire for a few minutes. Pour in a quart of stock or water, which must be boiling; season with pepper, salt, and a little grated nutmeg; boil up, and let it simmer till done. Pass through a colander, return it to the stewpan, add a pint and a half of milk and a table-spoonful of crushed tapioca. Stir well, and let all simmer for about twenty minutes, when it will be ready for serving. If too thick, add a little more stock or water.
A plain white vegetable soup of the sort Cassell's uses to demonstrate the principle of building flavour by sweating vegetables before liquid goes in. Nothing here is difficult; the measures and the straining step need translating.
- Imperial measuresThe quantities are imperial: a quart is 40 fl oz (about 5 cups) and a pint and a half of milk is 30 fl oz (just under 4 cups). Using US measures gives a noticeably thicker soup, which the last line anticipates.
- Half a stick of celeryBritish usage of "stick" was not fixed: it could mean a single rib or, in some kitchens, a whole head, so the amount intended is uncertain. Two or three ribs suits a pound of potatoes; the celery is background, not the main flavour.
- Sweat, do not brownThe point of the first stage is to steam the vegetables in butter with the lid on over low heat until they soften and smell sweet, five to eight minutes. Colour on the onion or leek will tint the finished soup and work against the pale, milky effect being aimed at.
- Boiling liquidThe instruction that the stock be boiling when it goes in is deliberate: it keeps the pan at temperature and shortens the cooking. Simmer 20 to 25 minutes, until a potato slice collapses under a spoon.
- "Pass through a colander"A colander of this period was used with a wooden spoon or ladle to force soft vegetables through the holes, effectively a coarse purée. A food mill or a sieve does the same job; a blender or stick blender is faster, though potato worked too hard in a blender turns gluey, so pulse briefly.
- Crushed tapiocaThis was pearl tapioca broken small, sold for thickening soups. Small pearl tapioca works, or use a scant tablespoon of tapioca starch slurried in cold milk. Either way it must have the full 20 minutes at a bare simmer to lose its raw taste and go clear.
- Once the milk is inKeep the heat low and stir often. Milk with starch in it catches on the base of the pan quickly and a scorched note will carry through the whole soup; a heavy saucepan (the "stewpan") is worth using for this stage.
- YieldAbout two quarts finished, enough for six as a first course. Nutmeg is easy to overdo here — a few scrapes only.
Potato soups thickened with milk run through nineteenth-century British cookery as everyday food, and this one teaches a sequence rather than a specialty: sweat the aromatics in fat, wet with boiling stock, cook, sieve, finish with dairy and a starch. The leek-and-potato combination is much older than any single named recipe, and this is essentially the domestic English version of it, unenriched by the cream and cold service that made vichyssoise famous abroad in the following century. The tapioca is the period detail: cassava starch is generally said to have become cheap and fairly widely available in British grocers by the second half of the 1800s, and household books recommended it, along with sago and arrowroot, as a lighter thickener than flour for milk soups. Dripping offered as an alternative to butter marks the book's intended reader, cooking with what the last roast had left behind.