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Burnt Onions
Peel one-half pound of onions, place in a saucepan with a breakfast cupful of water, and cook for five minutes. Add eight ounces of moist sugar and simmer gently until the mixture is almost black. Pour in one gill of boiling vinegar, stirring well with a wooden spoon, and it is then ready for use. It may be poured into bottles and kept if required.
This is not a dish but a kitchen staple: a dark onion caramel used to colour and deepen soups, gravies and sauces. Everything hinges on taking the sugar far enough without letting it turn acrid.
- Read "almost black" carefullyThe sugar must go past amber into a very dark, faintly bitter caramel, but a scorched batch tastes of ash and cannot be rescued. Pull it the moment the surface stops smelling sweet and starts smelling toasted, and work in a heavy pan so the heat is even.
- Adding the vinegarBoiling vinegar hitting molten caramel erupts in steam and spits. Have the vinegar genuinely at a boil, add it in a thin stream at arm's length with the pan off the heat, and keep the wooden spoon moving; cold vinegar will seize the caramel into a solid lump.
- Moist sugarThis is unrefined light brown sugar, still damp with molasses. Modern light brown sugar is the closest match; eight ounces is about a generous cup packed.
- A breakfast cupfulA breakfast cup ran larger than a teacup, about 10 fluid ounces, so call it 1 1/4 cups of water. The exact figure hardly matters here since it boils off before the caramel stage.
- A gillHalf a cup in American measure, 5 fluid ounces if the book is following British practice. Either falls within the workable range; start with 1/2 cup and add more if the syrup sets too stiff when cool.
- Which vinegarMalt or cider vinegar suits the flavour; distilled white is harsher but neutral. Ordinary modern 5 percent vinegar works, though the strength the original intended is not stated.
- Straining and yieldHalf a pound of onions gives soft, spent pieces that are best strained out before bottling unless you want texture. Expect roughly a cup of dark syrup, which is a season's worth given that it is used a teaspoon at a time.
- KeepingThe high sugar and vinegar make this shelf-stable in a clean, tightly closed bottle, though refrigeration keeps the flavour brighter. It thickens as it cools and will pour more easily if the bottle is stood in warm water.
Before commercial gravy browning was a fixture on every grocer's shelf, a professional kitchen made its own colouring, and burnt sugar was a common base: cheap, keeps well, and a few drops turn a pallid gravy the deep brown that diners read as richness. Adding onions gives the syrup a savoury edge, so it seasons as well as tints, in the same family as the bottled browning and caramel colour still sold today and as the burnt-sugar syrups used across the Caribbean and in West African cooking. A preparation like this sits among the recipes for dishes because it belongs to the unglamorous stock of things a large kitchen simply had on hand.