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 ↓
Kidney Toast
Ingredients
Directions
Blanch the kidneys in scalding water for 1 minute to remove strong taste, then dry them with a cloth.
Prepare a strong broth or gravy using bones or scraps, adding the glaze, and stew the kidneys until tender.
Remove the kidneys, drain them, and strain the cooking gravy into a bowl.
Pound the kidneys with some butter in a mortar until smooth, then pass through a sieve.
Skim any grease from the gravy, then melt 2 tablespoons of butter in a medium saucepan.
Stir in 1½ tablespoons of flour until creamy, then gradually add 1 tablespoon of the gravy.
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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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Pepper + flourtop 19% of all pairsSmell alikemoderateCooked together50,459 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Pepper + buttertop 21% of all pairsSmell alikemoderateCooked together85,593 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
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
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