Why it works: Pepper and lemon match in chemistry and in kitchens. They rank in the top 3% of all ingredient pairs, and cooks put them together in 27,047 recipes. Both carry trans-2-nonenal, which smells cardboard, fatty. The science ↓
Robart Sauce for Steaks
Ingredients
Directions
Make the sauce
In a saucepan or frying pan, melt the butter over medium heat.
Add the shredded onions and fry until brown, being careful not to burn them.
Stir in the flour and fry for another minute.
Season with pepper and coarse sea salt, then add the gravy.
Let it simmer for 10 minutes, then skim off the fat.
Add the mustard, vinegar, and lemon juice, and bring to a boil.
Serve
Pour the sauce around the steaks.
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.
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Pepper + lemontop 3% of all pairsSmell alikestrongCooked together27,047 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
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Onion + mustardtop 6% of all pairsSmell alikestrongCooked together9,259 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Mustard + vinegartop 7% of all pairsSmell alikemoderateCooked together14,067 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Pepper + mustardtop 9% of all pairsSmell alikemoderateCooked together15,430 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Mustard + lemontop 11% of all pairsSmell alikestrongCooked together3,816 recipes
Shared aroma: eucalyptol (eucalyptus, herbal).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Butter
- Adds richness and carries the onion flavour while it cooks.
- Onions
- Browning gives the sauce a deep, sweet, savoury base.
- Flour
- Thickens the sauce as it cooks with the butter and onions.
- Good gravy
- Forms the main liquid and savoury body of the sauce.
- Made mustard
- Adds sharp, pungent flavour that balances the richness.
- Vinegar
- Adds acidity that brightens the sauce and cuts through the fat.
The step that matters
Browning the onions. Onions turn brown through the Maillard reaction and caramelisation, which build deep flavour. Burnt onions turn bitter and can spoil the whole sauce, so keep the heat moderate and stir often.
Swap the lemon
How well each one fits the dish's main ingredients (butter, onion, flour, pepper, mustard, vinegar):
- Avocadofits better
- Limefits better
- Lemonthe original
- Mangofits about as well
Fit is the average pairing score against butter, onion, flour, pepper, 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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