Lemon Sauce
1 cup sugar 1 cup boiling water 1 tablespoon corn starch 1 tablespoon butter 1 1/2 tablespoons lemon juice 1/8 teaspoon salt Mix sugar, salt and corn starch, add water gradually, stir constantly; boil five minutes. Remove from fire, add butter and lemon juice. Creams, Custards, Etc.
A cornstarch-thickened dessert sauce of the plainest kind, and it works exactly as written. A few notes on technique and proportion.
- Mixing the starch dryWhisking the cornstarch with the sugar and salt before any liquid goes in is the whole trick — the sugar keeps the starch grains apart so they hydrate without lumping. Add the boiling water in a thin stream while stirring.
- "Boil five minutes"Cornstarch needs to reach a full boil to thicken properly and to cook out its raw, chalky taste, but five minutes at a hard rolling boil can thin the sauce again as the starch breaks down. Bring it to a bubble, then hold it at a bare simmer for two to three minutes until it is clear and glossy.
- Butter and juice go in off the heatBoth are added after the pan leaves the burner for good reason: prolonged heat dulls the fresh lemon flavour, and butter stirred in at the end gives the sauce its shine and body.
- Lemon quantityOne and a half tablespoons is the juice of about half a large lemon. It reads timid to a modern palate accustomed to sharper sauces; a little grated zest stirred in at the end, or more juice, is a defensible adjustment.
- "Remove from fire"Simply off the heat. The phrasing is a holdover from ranges where you moved the pan rather than turned a dial.
- Yield and servingRoughly a cup and a quarter to a cup and a half, enough for six modest servings. It is meant to be spooned warm over steamed or baked puddings — cottage pudding, gingerbread, a plain bread pudding — and it will thicken toward a soft jelly if refrigerated, so rewarm gently and stir.
Lemon sauce belongs to the family of cornstarch dessert sauces that became common in American cookbooks in the later nineteenth century, as commercially refined cornstarch became a pantry staple alongside the older egg-and-cream and flour-and-butter thickenings. Its purpose was economy: a hot sweet sauce turns a pan of plain steamed batter pudding or cottage pudding into a proper dessert without cream, eggs or much fruit.