Why it works: Leek and parsley match in chemistry and in kitchens. They rank in the top 5% of all ingredient pairs, and 759 recipes mention both. Both carry trans-2-hexenal, which smells green, leafy. The science ↓
The recipe
Ingredients
Contains: egg, milk, wheat (auto-detected from the ingredients and method; we can miss things, so check labels)
Directions
Make the soup
In a saucepan, melt the butter and lightly fry the sliced leeks without browning them.
Add 1 to 2 quarts of broth and cook until the leeks are well done.
Stir in 3 quarts of thickened chicken or veal broth.
Season with salt, pepper, nutmeg, and a pinch of sugar, then add the faggot of parsley.
Let it cook slowly for 25 minutes.
Remove the faggot, skim off the grease, and strain the soup through a fine sieve.
Return the soup to the saucepan to keep warm.
Finish and serve
In a bowl, dilute the egg yolks in the cream and add 2 tablespoons of butter.
Stir until the butter melts, then add the chopped chives.
Serve the soup with the cream mixture and fried bread crumbs on the side.
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 aroma chemistry they share, and how many recipes mention both.
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Leek + parsleytop 5% of all pairsAroma overlapstrongMentioned together759 recipes
Shared aroma: trans-2-hexenal (green, leafy).
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Pepper + parsleytop 2% of all pairsAroma overlapstrongMentioned together34,118 recipes
Shared aroma: 4'-methylacetophenone (bitter almond).
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Nutmeg + parsleytop 3% of all pairsAroma overlapstrongMentioned together5,062 recipes
Shared aroma: 4'-methylacetophenone (bitter almond).
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Butter + creamtop 3% of all pairsAroma overlapstrongMentioned together41,494 recipes
Shared aroma: delta-dodecalactone (sweet, creamy).
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Pepper + nutmegtop 4% of all pairsAroma overlapstrongMentioned together13,015 recipes
Shared aroma: 4'-methylacetophenone (bitter almond).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Leeks
- Cook down into the soft, sweet body of the soup.
- Egg yolks
- Thicken the cream mixture and give the finished soup a rich texture.
- Cream
- Adds richness and smooth mouthfeel to the enriched finish.
- Butter
- Adds fat and rich flavor to the leeks and the finishing mixture.
- Broth
- Forms the liquid base that carries the flavor of the soup.
The step that matters
Adding the egg yolk and cream mixture. Egg yolks thicken when heated gently; if the soup is boiling when they go in, they can scramble and curdle. Keep the soup hot but not boiling and stir steadily while adding the mixture.
Flavor stand-ins for the parsley
How well each one fits the dish's main ingredients (leek, butter, chicken, pepper, nutmeg, sugar, cream):
- Cinnamonbetter flavor fit
- Thymeabout as good a flavor fit
- Celeryabout as good a flavor fit
- Parsleythe original
Fit is the average pairing score against leek, butter, chicken, pepper, nutmeg, sugar, cream. Candidates are from the same food group and used in at least 100 recipes. This compares flavor only: it does not check the job the ingredient does in the dish (bulk, moisture, acidity, structure).
“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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