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Sauce

Robert Sauce

A savory sauce made with onion, butter, vinegar, brown gravy or flour and water, seasoned with salt, pepper, and French mustard.

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

Make the sauce

  1. Melt butter over medium heat in a skillet and add chopped onion.

  2. Fry onion until brown.

  3. Add vinegar and boil rapidly until nearly evaporated.

  4. If using gravy, stir it in now.

  5. If not using gravy, mix flour in skillet until browned, then add boiling water.

  6. Season sauce with salt and pepper.

  7. Simmer slowly for 15 minutes.

Finish and serve

  1. 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 the butter to add sweetness and savory depth to the sauce.
Vinegar
Adds acidity that sharpens the sauce and balances the rich fat and browned flavors.
Brown gravy
Provides the main body, savory flavor, and color of the sauce.
French mustard
Adds sharp, tangy flavor and aroma stirred in at the end.

The step that matters

Boil the vinegar until nearly evaporated. Rapid boiling drives off the sharp volatile vinegar so its acidity mellows rather than tasting harsh in the finished sauce.

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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