Why it works: Beans and onion match in chemistry and in kitchens. They rank in the top 7% of all ingredient pairs, and cooks put them together in 5,242 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
String Beans, Bretonne
Ingredients
Directions
Prepare
Prepare the string beans as in the previous recipe.
Cut the onions in half, trim the ends, and slice them finely.
Cook
In a saucepan, melt the butter and fry the onions until light brown.
Add the vinegar and cook until reduced by two-thirds.
Stir in the Espagnole sauce, string beans, and season with salt and pepper.
Cover the saucepan and let simmer slowly for 20 minutes.
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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Beans + oniontop 7% of all pairsSmell alikestrongCooked together5,242 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Beans + peppertop 11% of all pairsSmell alikemoderateCooked together4,733 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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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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Onion + vinegartop 14% of all pairsSmell alikemoderateCooked together18,226 recipes
Shared aroma: acetic acid (sour, vinegar).
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Vinegar + peppertop 14% of all pairsSmell alikemoderateCooked together27,814 recipes
Shared aroma: 4'-methylacetophenone (bitter almond).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Onions
- Frying until light brown builds sweetness and savory depth as the onions soften.
- Vinegar
- Reducing it by two-thirds concentrates its sharp acidity, balancing the richness of the sauce.
- Espagnole sauce
- Provides body and a rich, savory flavor that coats the beans and onions.
- Butter
- Fat for frying the onions, adding richness and helping them brown.
The step that matters
Reducing the vinegar by two-thirds. Cooking the vinegar down concentrates its acidity. If it is left too wet, the dish tastes sharp and thin; if over-reduced, it turns harsh and may scorch on the pan base.
Swap the beans
How well each one fits the dish's main ingredients (onion, butter, vinegar, sauce, pepper):
- Sesamefits better
- Black-eyed peafits about as well
- Beansthe original
- Soybeanfits about as well
Fit is the average pairing score against onion, butter, vinegar, sauce, 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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