Mint Sauce is a British sauce, though it is also widely popular throughout the English-speaking world. It is a traditional accompaniment to lamb.
Great European chefs see red when English-speakers ask for this green sauce in a restaurant. The Europeans see Mint Sauce as a nasty English-speakers’ invention, even though it isn’t: it’s one of the few surviving Roman recipes still being used today.
Mint is finely chopped up, and set aside to marinate in vinegar with a little sugar in it — it takes only 5 minutes to make.
The colour can vary. Fresh and some commercial versions can be green; home-preserved and some commercial ones can be brown.
You can also buy commercial brands in small bottles. This is often more convenient than making it, if only because making it requires only a handful of mint leaves, leaving you stuck with basically the whole bunch of mint still left.
Unless you have access to free, fresh mint in reasonable proportions (e.g. a handful clipped from a pot on the porch or your back garden), you might just as well get a bottle of decent mint sauce that will store well in the fridge for about the same price as a bunch of mint. Crosse & Blackwell and Colman’s both make perfectly good bottled mint sauces.
A dash of mint sauce is also good on peas or on a fresh fruit salad.
In any versions you make for home bottling / canning, ensure that the proportion of liquid ingredients is at least 50 % vinegar (higher is fine, too. Use vinegar of 5% acidity or higher.) That will help ensure a pH of 4.6 or lower, preventing any botulism spores present from germinating. All filled jars must then be heat processed in a boiling water bath to inactivate any mould spores, which could raise the pH, putting your sauce back in the danger zone.
1 cup of raw leaves = ½ cup of finely chopped leaves = ½ cup (125 ml / 4 ounces) of mint sauce Mint Sauce Recipe. Pick your own web site. Accessed November 2017 at http://pickyourown.org/MintSauce.htm
The Romans used a vinegar flavoured with the herb savoury in the same manner as we use mint sauce these days.