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Onion and Potato Soup
Slice two or three (large) onions.
Fry them in a tablespoon of butter or drippings until they are soft and red. Then add two tablespoons of flour and stir until it is a little cooked. To this add slowly a pint of boiling water, stirring all the time so it will be smooth. Boil and mash three goodsized potatoes. Add to them slowly a quart of scalded milk, stirring well. Add the potato mixture to the onion mixture. Season with salt and pepper. Let it get very hot and strain into a hot tureen. Sprinkle parsley over the top and serve with croutons.
A straightforward flour-thickened potato and onion soup from 1911. Two things decide whether it succeeds: how far you take the onions, and whether you strain it.
- Cook the onions properly"Soft and red" points to well-browned onions rather than merely softened ones, which is likely to take 20-30 minutes over medium-low heat, not the five minutes the terse wording suggests. This is where most of the flavour comes from; a tablespoon of butter is barely enough for two or three large onions, so use two.
- VolumesA pint of boiling water is 2 cups, a quart of scalded milk is 4 cups. That gives roughly 6 cups of liquid before reduction, or four to six servings.
- DrippingsBeef or bacon drippings were common household fats at the time and give the soup a savoury weight butter does not. The recipe names either without preference, so both are faithful.
- Scalded milkHeating milk to just below the boil was a standard step in period cookery, explained at the time in various ways, including guarding against souring and off-flavours in unpasteurized milk. With modern milk it is mainly a temperature matter: warming it keeps the soup from cooling when the two mixtures are combined.
- The rouxTwo tablespoons of flour to 2 cups of water is a thin binding, meant to hold the potato and milk in suspension rather than thicken on its own. Cook it a full minute before adding liquid or the soup tastes pasty.
- StrainingThe recipe strains into the tureen, which suggests the onion was treated as a flavouring rather than as a vegetable to be eaten. Press the solids firmly through a sieve. If you would rather keep the body, blend instead and skip straining, but expect a coarser soup.
- Do not boil after the milk goes inOnce combined, hold the soup just below a simmer. "Let it get very hot" is deliberate wording; a hard boil with milk and this little flour will curdle it.
- PotatoesBoil floury potatoes (russets or similar) and mash them dry before adding milk, or the soup goes gluey. Waxy potatoes resist mashing smooth and are harder to strain.
Onion and potato soups belong to the family of thickened milk soups that dominated American cookbooks around 1900, when the flour-and-fat roux plus scalded milk formula was, by most accounts, a staple of the emerging domestic science movement. The Butterick Publishing Company, better known for dress patterns and The Delineator, published cookbooks aimed at the same middle-class housekeeper, and the style here is characteristic: cheap staples, a technique that can be learned once and applied to a dozen vegetables, and a finish that makes the result presentable at table. The straining and the tureen, the parsley and the croutons, suggest a dish meant to be served as a proper first course rather than eaten from the pot; with leeks in place of onions it approaches the French potage.