This section is from the book "The Steward's Handbook And Guide To Party Catering", by Jessup Whitehead. Also available from Amazon: Larousse Gastronomique.
Chopped green mint, vinegar and sugar; mixed and served cold. This is the sauce for cold lamb and mutton in England and France, but is eaten with hot roast lamb in this country where cold meats are not in favor.
An'Old Bohemian'observes: "When I talk of mint sauce, I do not mean the wretched mess of a few imperfectly chopped dry mint-leaves swimming about in a sea of malt vinegar, with a few grains of raw sugar dissolved in it, which one gets in some dining-rooms, and occasionally even at private tables, and which has its admirers, too, among some chefs and blue ribbons, who coolly tell you that half an ounce of moist sugar will do for five fluid ounces of malt vinegar. I recommend the following recipe: Take a sufficiently large bunch of fresh green young mint to fill, when finely chopped, two to three table-spoonfuls; chop the rind of a good-sized lemon very fine, and add it to the mint in a sauce-tureen; to four ounces of best French vinegar add one ounce and a half of fresh lemon juice, and dissolve in this as much finely powdered best loaf-sugar as it will absorb; pour the solution over the mint in the tureen, and let it stand an hour or so".