Name: Sardine Sandwiches
Ingredients: 1 box of sardines; 2 hard-boiled eggs; ½ teaspoon French mustard; ½ teaspoon grated horseradish; buttered bread or cold biscuits

Why it works: Mustard and horseradish match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 1,832 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Sardine Sandwiches

Ingredients

Directions

Prepare

Chop the sardines finely.
Chop the hard-boiled eggs and season with French mustard and grated horseradish.
Mix the sardines and egg mixture well.

Assemble

Spread the mixture between thin slices of buttered bread or cold biscuits.

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.

Mustard + horseradishtop 1% of all pairs

Smell alikestrong

Cooked together1,832 recipes

Shared aroma: coumarin (sweet, hay).
Egg + breadtop 13% of all pairs

Smell alikemoderate

Cooked together22,662 recipes

Shared aroma: (e)-2-octenal (fatty, green).
Mustard + breadtop 16% of all pairs

Smell alikemoderate

Cooked together1,484 recipes

Shared aroma: 2-acetyl-1-pyrroline (popcorn, roasted).
Horseradish + breadtop 19% of all pairs

Smell alikemoderate

Cooked together240 recipes

Shared aroma: coumarin (sweet, hay).
Egg + horseradishtop 26% of all pairs

Smell alikelow

Cooked together694 recipes

Shared aroma: 2-methylbutyraldehyde (malty, chocolate).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Sardines: Provide the main savoury flavour and the filling's body.
Hard-boiled eggs: Add richness and a soft, creamy texture that binds the filling.
French mustard: Adds sharp, tangy flavour that cuts the richness of the fish and eggs.