Why it works: Lemon and walnut match in chemistry and in kitchens. They rank in the top 10% of all ingredient pairs, and cooks put them together in 2,149 recipes. Both carry 2-nonenal, which smells fatty, green. The science ↓
Lemon Pie
Ingredients
Directions
Make the filling
In a double boiler, combine the lemon rind, lemon juice, sugar, flour (or corn starch), egg yolks, water, and butter.
Cook until the mixture thickens.
Assemble and top
Once cooled, pour the filling into a pre-baked pie crust.
Beat the egg whites until stiff and spread them over the pie as meringue.
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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Lemon + walnuttop 10% of all pairsSmell alikestrongCooked together2,149 recipes
Shared aroma: 2-nonenal (fatty, green).
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Flour + buttertop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Flour + walnuttop 12% of all pairsSmell alikemoderateCooked together5,873 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Sugar + flourtop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
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Butter + walnuttop 15% of all pairsSmell alikemoderateCooked together6,832 recipes
Shared aroma: eucalyptol (eucalyptus, herbal).
Flour and butter 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
- Egg yolks
- Add richness and help thicken the filling as they cook.
- Flour or corn starch
- Thickens the lemon filling as it cooks and sets.
- Lemon juice
- Adds the sharp acidity that balances the sweetness of the filling.
- Sugar
- Sweetens the filling and offsets the tartness of the lemon.
- Egg whites
- Whipped into stiff peaks to form the airy meringue topping.
The step that matters
Cook until the mixture thickens. Starch needs to reach a full boil to gelatinize and set the filling, and egg yolks thicken as they heat. Undercooking leaves a runny filling, while overheating can curdle the yolks.
Swap the walnut
How well each one fits the dish's main ingredients (lemon, sugar, flour, egg, butter):
- Almondfits better
- Pistachiofits better
- Milletfits better
- Walnutthe original
Fit is the average pairing score against lemon, sugar, flour, egg, 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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