Onion Soup
1/2 pound Spanish onions 1 1/2 ounces butter 1/2 pint barley stock 1 ounce patent groats 1 quart milk Salt and pepper Cut the onion into thin slices, and fry it in the butter to a golden brown. Add the barley stock, and cook for twenty minutes. Mix the groats smoothly with a little of the milk, and boil the rest. When boiling, add the groats, and boil for ten minutes. Add to the onion. Season and serve.
A meatless onion soup thickened with oat groats rather than flour or bread — plain, but it depends on two things the text does not spell out: a properly browned onion and milk that never catches.
- Imperial measuresThis is a British book, so the half pint of stock is 10 fl oz (about 1 1/4 US cups) and the quart of milk is 40 fl oz (5 US cups). Using US pints and quarts gives a noticeably thinner soup.
- Patent groatsA prepared oat product of the period — oats milled fine, sold as an invalid and infant food. Fine oatmeal or oat flour is the direct equivalent; 1 ounce is roughly 3 to 4 tablespoons. Slaking it in cold milk before it meets the hot milk is what keeps it from lumping.
- Barley stockSimply the water pearl barley has been simmered in, lightly salted and strained. Make it ahead: 2 tablespoons barley to a pint of water, simmered 40 minutes. A light vegetable stock stands in, though it lacks the faint starchy body barley gives.
- Spanish onionsLarge, mild, pale-skinned onions. Half a pound is one big one. Slice thin and let them take a genuine golden brown in the butter over medium heat — ten to fifteen minutes. The recipe's whole flavour comes from this step, and rushing it on high heat gives scorched bitterness instead of sweetness.
- Boiling the milkMilk thickened with oat flour will catch on the bottom of the pan within a minute if unwatched. Use a heavy pan, keep it at a bare boil, and stir throughout the ten minutes.
- TextureAs written the soup keeps its onion slices. If a smooth soup is wanted, blend before seasoning; the groats give it enough body to hold together without cream.
- SeasoningMilk-based soups take more salt than they seem to. Season at the end, off the heat, and taste. A grating of nutmeg is period-appropriate and does the soup no harm.
- YieldRoughly 1 1/2 quarts — four generous bowls or six as a first course.
Meatless cookery of this sort belongs to a British tradition older than modern vegetarianism: Lenten and Friday cooking and invalid diets. Onion soup here is built on barley water and milk rather than beef broth, which is exactly the substitution such books were written to demonstrate. The patent groats are the giveaway of the period, being sold by the tin as nourishment for infants and convalescents, and cookery writers borrowed them as an all-purpose thickener that was thought more digestible than wheat flour. The result is closer to a mild oat-thickened onion chowder than to the cheese-crusted French soupe a l'oignon that now dominates the name.