Potato Soup
4 cups potatoes. 1 large purple-top turnip. 3 cups boiling water. 3½ cups scalded milk. 1 onion sliced.
Parsley. 1/4 cup butter. 1/3 cup flour. 2 teaspoons salt. 1/8 teaspoon pepper. 1/2 cup hot cream.
PROCESS: Wash, pare and cut potatoes in one-fourth inch slices. Wash, pare and cut turnip the same. Cover with boiling water and cook ten minutes; drain, add onion and three cups boiling water. Cook until vegetables are tender; drain and reserve water. Rub vegetables through strainer, add water, add milk. Reheat and bind with butter and flour cooked together. Add hot cream and seasonings. Turn into hot tureen and sprinkle with finely chopped parsley.
A straightforward cream-of-vegetable soup built on a milk base and a cooked butter-flour binding. The only fussy part is the double cooking of the vegetables, which is there for a reason.
- The first boil is not optionalThe ten-minute parboil and drain pulls the sulfurous edge off the turnip; the water is thrown away and fresh boiling water added. Skip it and the finished soup tastes sharp and cabbagey under the cream.
- Purple-top turnipThe standard market turnip of the period and still sold under that name. One large one is roughly 1 to 1.5 lb; buy a firm, heavy specimen, since old spongy turnips are bitter. This is not a rutabaga, which is larger, yellow-fleshed and much sweeter.
- Scalded milkHeated to just below a simmer, around 180F, when small bubbles ring the pan. With pasteurized milk this is now only about getting the milk hot so it does not chill the soup; heat it in a separate pan while the vegetables cook.
- Binding with butter and flourA quarter cup butter and a third cup flour is a blond roux. Cook them together two or three minutes to lose the raw flour taste, then whisk in a ladleful of the hot soup to loosen before returning it to the pot, or it will lump.
- Rubbing through a strainerA food mill or a stick blender does this in a fraction of the time. If you use a countertop blender, vent the lid and work in batches, since hot soup expands violently.
- Season by taste, not by the numbersTwo teaspoons salt is reasonable for roughly two quarts, but a full teaspoon of pepper is heavy for a delicate milk soup. Start with a quarter teaspoon of white pepper and build.
- Do not boil after the creamOnce the hot cream goes in, keep the pot below a simmer. A flour-bound milk soup will scorch on the bottom and taste of it throughout.
- YieldAbout two quarts, serving six to eight as a first course. It thickens noticeably as it stands; thin with hot milk when reheating.
Potato soup of this kind is characteristic of late nineteenth-century cooking-school practice, and the method here follows the pattern associated with the Boston school: vegetables cooked and sieved, milk scalded separately, the whole bound with a cooked butter-and-flour paste rather than thickened by starch alone. A similar binding turns up in the era's oyster, corn and clam "bisques," and it made a milk soup less likely to separate in a tureen on the table. The turnip is the interesting addition, giving a faint peppery sweetness that plain potato soup lacks; an autumn placement suits both vegetables, which were lifted in autumn and stored well in a cellar through the winter. Serving from a heated tureen with chopped parsley scattered over was a common presentation for a soup of this class in American household books of the period.