Why it works: Butter and flour are a kitchen classic. They rank in the top 12% of all ingredient pairs, and cooks put them together in 124,287 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓
Onion Soup Maigre
Ingredients
Directions
Prepare
Peel and dice the onions.
Make the soup
In a stewpan, melt the butter over medium heat.
Add the diced onions and fry until well cooked.
Stir in the flour and mix well.
Add the water and bring to a boil.
Cook until the onions are tender.
Season with salt and sugar, then 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.
-
Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Flour + sugartop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
-
Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
-
Butter + sugartop 17% of all pairsSmell alikemoderateCooked together98,233 recipes
Shared aroma: guaiacol (smoky, sweet).
-
Onion + flourtop 17% of all pairsSmell alikemoderateCooked together32,460 recipes
Shared aroma: isobutyraldehyde (malty, green).
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
- Form the body of the soup and, as they cook down, add sweetness and savoury flavour.
- Butter
- Adds fat for frying the onions, carrying flavour and giving a rich mouthfeel.
- Flour
- Thickens the soup as it is cooked with the butter and then the water.
The step that matters
Stir in the flour and mix well. Flour must be fully blended into the butter and onions before the water goes in. Stirring it into the hot fat coats the starch grains so they hydrate evenly, which prevents lumps and gives a smooth, thickened broth.
Swap the onion
How well each one fits the dish's main ingredients (butter, flour, sugar):
- Arrowrootfits better
- Shallotfits better
- Sweet potatofits better
- Onionthe original
Fit is the average pairing score against butter, flour, sugar. 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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