Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Dressed Fish
Ingredients
Directions
Make the sauce
Chop the onion and fry until brown with herbs and flour in butter.
Stir in the peppers, mace, a pinch of salt, and the stock.
Add the eel pieces and let it stew slowly for about 30 minutes until cooked.
Finish and serve
Remove the fish with a slotted spoon and keep it warm in the oven.
Add ketchup to the sauce, bring it to a boil, strain it over the eel, and serve.
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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Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Butter + fishtop 12% of all pairsSmell alikemoderateCooked together4,488 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Flour + ketchuptop 13% of all pairsSmell alikemoderateCooked together2,435 recipes
Shared aroma: ethanol (alcoholic, ethereal).
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Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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
- Eel
- Is the main protein, cooked gently in the stock until tender.
- Butter
- Carries the frying of the onion and herbs, adding richness and browning flavour.
- Flour
- Thickens the sauce as it cooks with the butter and onion.
- Onion
- Browns in butter to build the savoury base of the sauce.
- Ketchup
- Adds sweetness and acidity to the finished sauce.
The step that matters
Frying the onion, herbs and flour until brown. The flour must cook in the butter long enough to lose its raw taste and help thicken the sauce, while the onion browns for depth. Burning turns the base bitter and dark.
Swap the mace
How well each one fits the dish's main ingredients (onion, pepper, butter, flour, ketchup, fish):
- Capersfits better
- Parsleyfits better
- Celeryfits better
- Macethe original
Fit is the average pairing score against onion, pepper, butter, flour, ketchup, fish. 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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