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Sauce

Morcan’s Tartan Sauce

A tartan sauce made with mustard, salt, cayenne, egg yolk, oil, vinegar, pickles, capers, herbs, and celery.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 12 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 sauce

  1. In a bowl, mix the dry mustard, coarse sea salt, and cayenne pepper. Add the yolk of the raw egg and mix well.

  2. Slowly add the sweet oil, drop by drop, stirring until thick.

  3. Add vinegar to taste.

  4. Stir in the chopped cucumber pickles, capers, parsley, leek, and celery.

  5. If the sauce is too thick, add cold water to reach desired consistency.

Rest and serve

  1. 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
Emulsifies the oil and vinegar so the sauce becomes thick and stable.
Sweet oil
Forms the body of the sauce and gives it a rich, smooth texture.
Dry mustard
Adds sharp flavour and helps stabilise the emulsion.
Vinegar
Adds acidity that brightens the rich oil and egg.
Capers
Add briny, sharp flavour that cuts through the richness.

The step that matters

Slowly add the sweet oil, drop by drop, stirring until thick. Adding oil too fast overwhelms the egg yolk, so the emulsion breaks and the sauce stays runny or separates. Slow addition while stirring lets tiny oil droplets disperse evenly in the yolk, producing a thick, stable 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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