French Mustard
Work together (until smooth) three tablespoonfuls of mustard and one of sugar, then add one egg which has been beaten, one teacupful of good vinegar, putting in a small quantity at a time to prevent its being lumpy. Beat all together until very smooth; place on the stove and cook only a few moments, stirring all the time; as soon as it becomes cool add one tablespoonful of olive oil, which must be worked in very smooth.
A cooked, custard-thickened prepared mustard rather than the simple flour-of-mustard-and-water paste of English tables. The whole thing hangs on cooking the egg without scrambling it.
- "Mustard" means dry mustardThree tablespoonfuls of mustard here is ground mustard powder, not a spoonable prepared mustard from a jar. Colman's or any plain yellow mustard flour works; the heat is developed by the liquid, not the cooking.
- TeacupfulA teacup in a book of this era is smaller than a modern measuring cup; equivalents vary from book to book, so reckon somewhere between about 4 and 6 fl oz. Cider or white wine vinegar suits the mixture better than harsh distilled vinegar.
- The hinge: gentle heat"Cook only a few moments" means thicken, not boil. Keep it over low heat or a bain-marie, stirring constantly, until it just coats the spoon; let it get much hotter and the egg curdles and the mustard turns grainy and will not come smooth again.
- Add vinegar gradually, as writtenThe instruction to add the vinegar a little at a time is not fussiness — dry mustard hydrated all at once forms stubborn lumps that no amount of later beating will break down.
- Oil goes in coldThe tablespoon of olive oil is beaten into the cooled mixture, as an emulsion. Warm mustard will let the oil separate and pool on top.
- Yield and keepingAbout a cupful. Because it contains cooked egg, store it in a covered jar in the refrigerator and use it inside a week or two rather than treating it as a shelf-stable condiment.
- Let it restFreshly mixed mustard is aggressively sharp and slightly bitter. A day in the cold rounds the flavor considerably.
In nineteenth-century British and American cookbooks "French mustard" was generally less a specific recipe than a category: a smooth, mild, vinegar-based prepared mustard set against the fierce dry-mixed English kind, the name apparently nodding to French mustards such as those of Dijon and Bordeaux, which reached English-speaking kitchens as imports. Home versions like this one, thickened with egg and softened with sugar and oil, aimed at something of that texture and mildness using pantry staples. A mustard of this kind belonged with cold meats, chops and salad dressings.