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Sauce

Robert Sauce

A savory sauce made with onions, butter, vinegar, stock, roux, mustard, pepper, and sea salt.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 8 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

Prepare the onions

  1. Cut the onions into small pieces.

  2. Fry the onions in butter in a frying pan.

  3. Drain off the butter.

Make the sauce

  1. Add vinegar to the frying pan and simmer for 10-15 minutes to reduce acidity.

  2. Add a little stock or water and stir.

  3. Thicken the sauce with a little brown roux.

  4. Stir in mustard, pepper, and salt.

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. Mustard + peppertop 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. Onion + vinegartop 14% of all pairs
    Smell alikemoderate
    Cooked together18,226 recipes

    Shared aroma: acetic acid (sour, vinegar).

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

What each ingredient does

Onions
Soften and sweeten as they fry, forming the flavour base of the sauce.
Butter
Fat that fries the onions and carries flavour into the sauce.
Vinegar
Adds acidity, sharpness, and tang that balances the rich fried onions.
Brown roux
Flour and fat cooked together to thicken the sauce and add body.
Mustard
Adds sharp, pungent flavour and aroma to the finished sauce.

The step that matters

Simmering the vinegar. Simmering the vinegar for the full 10-15 minutes lets its sharp acidity mellow and evaporate somewhat, so the sauce tastes balanced rather than harsh. Cooking it too briefly leaves a sour, raw edge that the later thickening and seasoning cannot fully hide.

Swap the onion

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

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

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