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French Mustard

A mustard condiment made with egg, butter, sugar, salt, mustard, vinegar, and cayenne pepper, thickened over a double boiler.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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Why it works: Mustard and vinegar are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 14,067 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓

French Mustard

Ingredients

Directions

Prepare

  1. Beat the egg in a bowl.

  2. Dissolve the mustard in a little vinegar.

Cook and thicken

  1. Add the other ingredients to the bowl.

  2. Place the bowl over a double boiler or a bowl over a kettle.

  3. Stir until the mixture thickens.

Recipe from a historical cookbook (Internet Archive).

Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.

  1. Mustard + vinegartop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  2. Mustard + peppertop 9% of all pairs
    Smell alikemoderate
    Cooked together15,430 recipes

    Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

  3. Vinegar + peppertop 14% of all pairs
    Smell alikemoderate
    Cooked together27,814 recipes

    Shared aroma: 4'-methylacetophenone (bitter almond).

  4. Sugar + vinegartop 15% of all pairs
    Smell alikemoderate
    Cooked together20,806 recipes

    Shared aroma: beta-damascenone (apple, rose).

  5. Egg + buttertop 17% of all pairs
    Smell alikemoderate
    Cooked together118,967 recipes

    Shared aroma: decanal (soap, orange peel).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Egg
Its proteins set as they heat, thickening the sauce.
Mustard
Provides the sharp, pungent flavor that defines the sauce.
Vinegar
Adds acidity that sharpens the flavor.
Sugar
Softens the sharpness of the vinegar and mustard.
Butter
Adds richness and a smoother texture.

The step that matters

Keep the heat gentle. Egg proteins thicken the mixture as they warm, but if the heat is too high they curdle and turn grainy. Stir constantly over the gentle steam of the double boiler so the sauce thickens smoothly.

Swap the mustard

How well each one fits the dish's main ingredients (egg, butter, sugar, vinegar, pepper):

  1. Capsicumfits better
  2. Mustardthe original
  3. Cucumberfits about as well
  4. Shallotfits less well

Fit is the average pairing score against egg, butter, sugar, vinegar, pepper. Candidates are from the same food group and used in at least 100 recipes.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.

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