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Sauce Robert

A brown onion sauce with butter, flour, stock, mustard, and vinegar, served with roast pork.

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 ↓

Sauce Robert

Ingredients

Directions

Make the sauce

  1. Melt the butter in a saucepan over low heat.

  2. Add the chopped onions and cook until browned.

  3. Sprinkle the flour over the onions and stir well.

  4. Gradually add the stock while stirring continuously.

  5. Leave the saucepan uncovered and reduce the sauce for 20 minutes.

  6. Remove the saucepan from the heat.

Finish and serve

  1. In a separate bowl, mix the mustard with the vinegar.

  2. Stir the mustard mixture into the sauce.

  3. Serve in a sauceboat with roast pork.

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. Mustard + vinegartop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: isobutyraldehyde (malty, green).

  4. Flour + mustardtop 13% of all pairs
    Smell alikemoderate
    Cooked together5,066 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: acetic acid (sour, vinegar).

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

Onions
Browning in the butter builds deep flavour and sweetness as the sugars caramelise.
Flour
Thickens the stock into a smooth sauce body when stirred into the fat and onions.
Butter
Carries the onions while they brown and adds richness to the finished sauce.
Stock
Forms the liquid base that the flour thickens and the reduction concentrates.
Mustard
Adds a sharp, pungent note that cuts through the richness of the sauce.

The step that matters

Adding the stock gradually while stirring. Adding liquid slowly while stirring keeps the flour dispersed, so lumps do not form and the sauce thickens evenly.

Swap the onion

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

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

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