Name: Sardine Sandwiches
Ingredients: boneless sardines; yolks of hard boiled eggs; coarse sea salt; cayenne pepper; lemon juice; olive oil or melted butter; buttered bread

Why it works: Pepper and lemon match in chemistry and in kitchens. They rank in the top 3% of all ingredient pairs, and cooks put them together in 27,047 recipes. Both carry trans-2-nonenal, which smells cardboard, fatty. The science ↓

Sardine Sandwiches

Ingredients

Directions

Make the filling

Mash the boneless sardines into a paste.
Mix in an equal quantity of yolks of hard boiled eggs that have been rubbed through a sieve.
Season the mixture with coarse sea salt, cayenne pepper, and a few drops of lemon juice.
Moisten the mixture with olive oil or melted butter.

Assemble

Spread the mixture between thin slices of buttered bread.

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.

Pepper + lemontop 3% of all pairs

Smell alikestrong

Cooked together27,047 recipes

Shared aroma: trans-2-nonenal (cardboard, fatty).
Lemon + olivetop 7% of all pairs

Smell alikemoderate

Cooked together11,922 recipes

Shared aroma: 3-hexenal (apple, fruity).
Olive + breadtop 9% of all pairs

Smell alikemoderate

Cooked together1,091 recipes

Shared aroma: 2-undecenal (sweet).
Pepper + olivetop 11% of all pairs

Smell alikemoderate

Cooked together30,263 recipes

Shared aroma: 2,4-decadienal (seaweed).
Egg + breadtop 13% of all pairs

Smell alikemoderate

Cooked together22,662 recipes

Shared aroma: (e)-2-octenal (fatty, green).

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

What each ingredient does

Boneless sardines: Provide the main savoury fish flavour and form the base of the paste.
Yolks of hard boiled eggs: Add richness and a smooth, creamy texture to the paste.
Olive oil or melted butter: Adds moisture and fat, loosening the paste and making it spreadable.
Lemon juice: Adds acidity that brightens the rich fish flavour.

“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.