Mint Sauce

A three-ingredient sauce with no quantities given, which is how most Victorian cookery books treated it. The proportions below are the conventional ones, and the timing note matters more than the measuring.

• Working proportionsThe recipe gives none, so these are a starting point: for a sauce-tureen's worth, about 4 tablespoons of finely chopped mint leaves, 1 to 2 teaspoons of sugar and 4 to 6 tablespoons of vinegar. Enough to go round a joint of lamb.
• Chop fast, chop dryThe instruction to work quickly with a sharp knife is the hinge of the recipe. Bruised mint oxidises and blackens; a dull blade crushes rather than cuts, and wet leaves release juice that dulls the colour further. Dry the leaves well and chop in one brisk pass.
• Dissolve the sugar firstThe recipe puts mint and sugar in the tureen and pours the vinegar over, but stirring the sugar into the vinegar until it has gone before adding the mint avoids grit in the tureen. A tablespoon of boiling water helps it dissolve.
• Which vinegarMalt was the ordinary household vinegar in Victorian England, and gives the traditional flavour; white wine or cider vinegar makes a lighter sauce. If yours is harsh, cut it with a little water rather than adding more sugar.
• Mint varietySpearmint is the mint meant here and the one to use. Peppermint is too aggressive and reads as confectionery against roast lamb.
• Standing timeThe sauce is better after 30 minutes to an hour, which lets the mint scent the vinegar. Make it the same day, though: kept overnight the leaves turn drab and the flavour goes flat and pickled.
• "Float in a liquid"This is the test to aim for. The leaves should be suspended and moving, not sitting in a damp paste. Add vinegar until a spoon drawn through the tureen leaves no channel behind it.