Why it works: Milk and butter are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓
Onion Sauce
Ingredients
Directions
Cook the onions
Peel and quarter the onions.
Place them in a saucepan with ½ cup of milk.
Boil until the onions are tender, about 1 hour.
Strain the milk into a basin.
Finish the sauce
Chop the onions finely.
Melt ½ tablespoon of butter in the saucepan.
Add the chopped onions to the melted butter, then stir.
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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Milk + buttertop 7% of all pairsSmell alikemoderateCooked together81,283 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Onion + milktop 20% of all pairsSmell alikemoderateCooked together13,418 recipes
Shared aroma: hexanal (green, grassy).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Onions
- Provide the main body and sweet, savoury flavour of the sauce as they soften.
- Milk
- Supplies the liquid that cooks the onions and carries their flavour into the sauce.
- Butter
- Adds fat for richness and a smooth mouthfeel, and helps carry the onion flavour.
The step that matters
Boil until the onions are tender. Milk scorches and sticks to the base of the pan if the heat is too high. Keep it at a gentle boil and stir so the milk does not burn while the onions soften.
Swap the onion
How well each one fits the dish's main ingredients (milk, butter):
- Potatofits better
- Asparagusfits about as well
- Leekfits about as well
- Onionthe original
Fit is the average pairing score against milk, butter. 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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