Horse-radish Sauce

A thick, bread-thickened horseradish sauce of the sort served with boiled beef or tongue. The whole point of it is the heat of the root, which is fragile, so the order of operations matters more than the quantities.

• Heat it gently, brieflyGrated horseradish loses its pungency fast once it goes above a simmer; the volatile compounds that give it bite cook off. Warm the mixture through over low heat and serve it, rather than holding it hot on the stove.
• Acid goes in last, off the heatAcid goes in last -- the lemon juice and vinegar are added after the mixture is hot. Acid does help fix the sharpness of freshly grated horseradish, so the order is likely deliberate, though the recipe gives no reason.
• The White SauceWhite sauce in books of this period is generally a roux of a tablespoon or two each of butter and flour cooked with a cup of milk and seasoned with salt; a modern medium bechamel is the closest equivalent. Check the book's own White Sauce entry for its proportions.
• The salt is incompleteThe line reads "teaspoon salt" with the fraction dropped in printing, as often happened with the vulgar fractions in these books. Half a teaspoon is a reasonable starting point given the white sauce is already seasoned; add to taste at the end.
• Fresh root, not the jarPrepared horseradish from a jar is already cut with vinegar and salt, so a cup of it will make a thin, sour sauce. Use a piece of fresh root, peeled and grated on a fine grater or in a processor, and grate it in a ventilated spot -- the fumes are genuinely eye-watering.
• Soft bread crumbsThese mean the crumb of day-old white bread torn or rubbed into soft flakes, not dry toasted crumbs. Dry crumbs will absorb far more liquid and give a paste; if that is all you have, use half as much.
• Yield and servingRoughly two to two and a half cups, a generous amount for a condiment, alongside boiled beef, roast beef, tongue or corned beef. It thickens as it stands; loosen with a spoonful of milk or cream when reheating.