Celery Dressing

A boiled dressing of the sort that stood in for mayonnaise before commercial jars existed. It is thickened by egg alone, so the whole recipe hinges on how you apply the heat.

• Do not actually boil it"Boil" here means bring to the point of thickening. Two eggs in two cups of liquid will curdle at a hard boil; cook over low heat or in a double boiler, stirring constantly, until it coats the back of a spoon, then pull it off at once and cool.
• Mixed mustardNot dry mustard powder. "Mixed" means mustard already made up with vinegar or water — an English-style prepared mustard is the closest match. If you only have powder, use about half a teaspoon slaked in a little water.
• The vinegarA full cup of vinegar to a cup of milk makes a sharp dressing by modern taste. Nineteenth-century household vinegar was often cider vinegar of variable strength, so the sourness the writer expected may not match what a modern bottle gives you. Cider vinegar is the better choice, and the acid is also what curdles milk on contact, so warm the two together gently rather than dumping cold vinegar into hot milk.
• Milk or creamCream gives a smoother, more forgiving result — the extra fat buffers both the acid and the heat. Whole milk works but is likelier to look grainy; a quick whisk or a blitz with an immersion blender will bring it back.
• No sugar, no flourMany later boiled dressings carry sugar and a spoon of flour for body. This one has neither, so expect a thin, pouring consistency and a frankly tart flavor. That is correct, not a failure.
• Yield and useMakes roughly two cups. The name refers to what it dresses, not what is in it: pour it cold over sliced raw celery, or over celery mixed with cold chicken or boiled potato.
• KeepingAn egg-and-dairy dressing, cooked but not shelf-stable. Refrigerate and use within three or four days.