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Sauce

Robert Sauce

A savory sauce made with onion, butter, vinegar, brown gravy, mustard, salt, and pepper.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Onion and mustard match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Robert Sauce

Ingredients

Directions

  1. Fry the chopped onion in butter until brown.

  2. Add vinegar and boil until nearly evaporated.

  3. Stir in brown gravy or, if using flour, first brown the flour, then mix in boiling water.

  4. Season with salt and pepper, and simmer for 15 minutes.

  5. Just before serving, stir in French mustard.

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. Onion + mustardtop 6% of all pairs
    Smell alikestrong
    Cooked together9,259 recipes

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

  2. Vinegar + mustardtop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Pepper + mustardtop 9% of all pairs
    Smell alikemoderate
    Cooked together15,430 recipes

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

  4. Onion + peppertop 11% of all pairs
    Smell alikemoderate
    Cooked together68,474 recipes

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

  5. Butter + flourtop 12% of all pairs
    Smell alikelow
    Cooked together124,287 recipes

    Shared aroma: isobutyraldehyde (malty, green).

Butter and flour barely smell alike, yet cooks put them together in 124,287 recipes: they work on texture and structure more than aroma.

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

What each ingredient does

Onion
Browns in butter to build savoury, sweet depth as the base of the sauce.
Vinegar
Adds acidity that sharpens the sauce and balances its richness.
Brown gravy
Supplies the main liquid and savoury body of the sauce.
French mustard
Adds sharp, pungent flavour stirred in at the end.

The step that matters

Reducing the vinegar. Boiling the vinegar until nearly evaporated drives off its sharp volatile harshness, leaving acidity that balances the sauce instead of overpowering it.

Swap the onion

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

  1. Shallotfits better
  2. Horseradishfits better
  3. Radishfits better
  4. Onionthe original

Fit is the average pairing score against butter, vinegar, flour, pepper, mustard. 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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