Name: W Duke of York's Universal Sauce
Ingredients: hard dried toast; 1 tablespoon peppercorns; 1 cup chopped parsley (or any other herb); 2 teaspoons coarse sea salt; 1 small teacupful of water; 1 teaspoon white vinegar; 1 teaspoon tarragon vinegar or lemon juice

Why it works: Parsley and tarragon match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 1,563 recipes. Both carry estragole, which smells anise, licorice. The science ↓

W Duke of York's Universal Sauce

Ingredients

hard dried toast
1 tablespoon peppercorns
1 cup chopped parsley (or any other herb)
2 teaspoons coarse sea salt
1 small teacupful of water
1 teaspoon white vinegar
1 teaspoon tarragon vinegar or lemon juice

Directions

Pound the hard dried toast and peppercorns in a mortar.
Boil the mixture with the chopped parsley and coarse sea salt in the water.
Add the white vinegar and tarragon vinegar or lemon juice.
Stir well and serve.

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.

Parsley + tarragontop 1% of all pairs

Smell alikestrong

Cooked together1,563 recipes

Shared aroma: estragole (anise, licorice).
Vinegar + tarragontop 7% of all pairs

Smell alikemoderate

Cooked together2,547 recipes

Shared aroma: isobutyraldehyde (malty, green).
Parsley + vinegartop 16% of all pairs

Smell alikemoderate

Cooked together6,477 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

Hard dried toast: Thickens the sauce and gives it body as it breaks down in the liquid.
Peppercorns: Adds pungent, sharp aroma and heat to the sauce.
Parsley: Contributes fresh, green flavour and aroma; any other herb can replace it.
White vinegar: Adds acidity that brightens the sauce and balances its richness.
Tarragon vinegar or lemon juice: Adds further acidity and a fresh, bright note to the sauce.