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 ↓
Curry Sauce
Ingredients
Directions
Cook the base
In a skillet, melt the butter over medium heat.
Add the chopped onion and fry until brown.
Stir in the flour and curry powder, cooking for 1 minute.
Make the sauce
Gradually add the stock, then season with salt and pepper.
Simmer for 5 minutes, then strain 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.
Photo for illustrative purposes only · Contact us to use it
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.
-
Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Butter + oniontop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
-
Flour + oniontop 17% of all pairsSmell alikemoderateCooked together32,460 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Flour + peppertop 19% of all pairsSmell alikemoderateCooked together50,459 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
- Butter
- Carries fat that blooms the curry powder and adds richness to the sauce.
- Flour
- Thickens the sauce as its starch swells in the hot liquid.
- Curry powder
- Provides the main spiced aroma and flavor of the sauce.
- Onion
- Browning builds sweetness and depth in the sauce base.
- Stock
- Forms the liquid that becomes the body of the sauce.
The step that matters
Gradually add the stock. Flour thickens by swelling in liquid, and adding stock slowly while stirring lets the starch disperse evenly, which prevents lumps in the sauce.
Swap the onion
How well each one fits the dish's main ingredients (butter, flour, pepper):
- Shallotfits better
- Chivefits better
- Capsicumfits better
- Onionthe original
Fit is the average pairing score against butter, flour, 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.
More curry sauce recipes
You might also like
The free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.

Tomato Soup526 recipes
Brown Bread461 recipes
Mutton Broth292 recipes
Yorkshire Pudding264 recipes