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Sauce

Morcan’s Tartan Sauce

A tangy mustard-based sauce with cucumber pickles, capers, parsley, and shallot, thickened with egg yolk and sweet oil.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 11 ingredients
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Why it works: Capers and shallot match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 405 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Morcan’s Tartan Sauce

Ingredients

Directions

Make the emulsion

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

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

  3. Slowly add the sweet oil, stirring until thick.

  4. Thin the mixture with vinegar to your desired consistency.

Add the chopped ingredients

  1. Chop the cucumber pickles, capers, parsley, and shallot or leek finely.

  2. Stir the chopped ingredients into the sauce.

  3. If the sauce is too thick, add cold water to thin it.

Rest and serve

  1. Let the sauce sit for one 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. Capers + shallottop 1% of all pairs
    Smell alikestrong
    Cooked together405 recipes

    Shared aroma: coumarin (sweet, hay).

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

    Shared aroma: coumarin (sweet, hay).

  3. Mustard + shallottop 1% of all pairs
    Smell alikestrong
    Cooked together859 recipes

    Shared aroma: eucalyptol (eucalyptus, herbal).

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

    Shared aroma: coumarin (sweet, hay).

  5. Parsley + shallottop 1% of all pairs
    Smell alikestrong
    Cooked together3,737 recipes

    Shared aroma: 2,4-decadienal (seaweed).

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 mustard so the sauce thickens and holds together.
Sweet oil
Forms the body of the sauce, giving it richness and a thick texture.
Mixed mustard
Helps stabilise the emulsion and adds sharp, pungent flavour.
Vinegar
Adds acidity that brightens the sauce and sets its final consistency.
Capers
Add briny, sharp bites of flavour that cut through the richness of the oil.

The step that matters

Slowly add the sweet oil. Oil added too quickly to the egg yolk and mustard cannot be absorbed into the emulsion, so the sauce may split and fail to thicken. Adding it in a slow, steady stream while stirring lets the droplets disperse fully.

Swap the cucumber

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

  1. Horseradishfits better
  2. Chivefits better
  3. Kalefits better
  4. Cucumberthe original

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