Name: Parsley Sauce
Ingredients: 1 tablespoon flour; ¼ pound butter; boiling water; fresh parsley

Why it works: Flour and butter 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 ↓

Parsley Sauce

Ingredients

1 tablespoon flour
¼ pound butter
boiling water
fresh parsley

Directions

Mix the flour and butter together.
Pour boiling water over the mixture.
Boil the parsley for 3 to 5 minutes.
Squeeze and chop the parsley finely.
Add the chopped parsley to the butter mixture.

Recipe from a historical cookbook (Internet Archive).

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.

Flour + buttertop 12% of all pairs

Smell alikelow

Cooked together124,287 recipes

Shared aroma: isobutyraldehyde (malty, green).
Flour + parsleytop 12% of all pairs

Smell alikemoderate

Cooked together16,675 recipes

Shared aroma: isobutyraldehyde (malty, green).
Butter + parsleytop 15% of all pairs

Smell alikemoderate

Cooked together28,563 recipes

Shared aroma: trans-2-hexenal (green, leafy).

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

Flour: Thickens the sauce by swelling in liquid and forming a smooth body.
Butter: Adds richness and a silky mouthfeel to the sauce.
Fresh parsley: Provides the main herbal flavour and green colour of the sauce.