Why it works: Watercress and mustard match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 293 recipes. Both carry coumarin, which smells sweet, hay. The science ↓
Green Butter
Ingredients
Directions
Prepare the greens
Wash the watercress, mustard, cress, and parsley.
Boil in a saucepan of water with a pinch of baking soda and a little salt for 5 minutes.
Drain and press out all the water.
Make the butter
Pound in a mortar with the butter and seasonings.
Rub through a fine sieve.
Finish
Put into a piping bag with a small rose pipe for decorating.
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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Watercress + mustardtop 1% of all pairsSmell alikestrongCooked together293 recipes
Shared aroma: coumarin (sweet, hay).
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Watercress + parsleytop 2% of all pairsSmell alikestrongCooked together469 recipes
Shared aroma: coumarin (sweet, hay).
-
Mustard + parsleytop 8% of all pairsSmell alikestrongCooked together2,588 recipes
Shared aroma: trans-2-hexenal (green, leafy).
-
Butter + parsleytop 15% of all pairsSmell alikemoderateCooked together28,563 recipes
Shared aroma: trans-2-hexenal (green, leafy).
-
Butter + mustardtop 22% of all pairsSmell alikemoderateCooked together8,003 recipes
Shared aroma: guaiacol (smoky, sweet).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Watercress
- Provides the green colour and a fresh, peppery flavour to the butter.
- Fresh butter
- Forms the rich base that carries the greens and seasonings.
- Mustard
- Adds a sharp, peppery bite that balances the richness of the butter.
The step that matters
Press out all the water. Leftover water dilutes the butter and can make the green mixture watery and hard to pipe. Pressing the greens dry keeps the butter firm and the flavour concentrated.
Swap the mustard
How well each one fits the dish's main ingredients (watercress, butter, parsley):
- Shallotfits better
- Chivefits better
- Horseradishfits better
- Mustardthe original
Fit is the average pairing score against watercress, butter, parsley. 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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