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Sauce

Morcan’s Tartan Sauce

A mustard-based sauce with egg yolk, oil, vinegar, pickles, capers, parsley, and leek.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 11 ingredients
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Why it works: Mustard and capers match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 624 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Morcan’s Tartan Sauce

Ingredients

Directions

Make the emulsion

  1. In a bowl, mix mustard, salt, and cayenne pepper.

  2. Add the yolk of the raw egg and mix well.

  3. Slowly add sweet oil, stirring until thick.

  4. Thin the mixture with vinegar.

Finish and rest

  1. Chop the pickles, capers, parsley, and leek finely and stir into the sauce.

  2. If the sauce is too thick, add cold water.

  3. Let the sauce sit for about an hour before serving.

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 + caperstop 1% of all pairs
    Smell alikestrong
    Cooked together624 recipes

    Shared aroma: coumarin (sweet, hay).

  2. Capers + parsleytop 1% of all pairs
    Smell alikestrong
    Cooked together1,550 recipes

    Shared aroma: coumarin (sweet, hay).

  3. Capers + leektop 1% of all pairs
    Smell alikestrong
    Cooked together27 recipes

    Shared aroma: coumarin (sweet, hay).

  4. Pepper + parsleytop 2% of all pairs
    Smell alikestrong
    Cooked together34,122 recipes

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

  5. Cucumber + caperstop 3% of all pairs
    Smell alikestrong
    Cooked together303 recipes

    Shared aroma: coumarin (sweet, hay).

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

What each ingredient does

Egg yolk
Acts as an emulsifier, holding the oil and vinegar together so the sauce becomes thick and smooth.
Sweet oil
Provides the fat that gives the sauce its rich body and creamy texture.
Mixed mustard
Adds sharpness and helps stabilise the emulsion so it does not separate.
Vinegar
Adds acidity that brightens the sauce and thins it slightly.

The step that matters

Adding the oil slowly. Oil must be added a little at a time while stirring so the egg yolk can disperse it into tiny droplets. Adding it too fast makes the emulsion break, leaving a greasy, separated sauce.

Swap the leek

How well each one fits the dish's main ingredients (mustard, pepper, egg, vinegar, cucumber, capers, parsley):

  1. Shallotfits better
  2. Horseradishfits better
  3. Lettucefits better
  4. Leekthe original

Fit is the average pairing score against mustard, pepper, egg, vinegar, cucumber, capers, parsley. 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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