Name: Sardine Sandwiches
Ingredients: 1 box sardines, drained and boned; 3 hard boiled egg yolks; ½ teaspoon salt; a bit of pepper; 2 teaspoons lemon juice; thin slices of 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

Prepare the filling

Mash the sardines to a paste.
In a bowl, mash the yolks of the hard boiled eggs and season with salt, pepper, and lemon juice.
Add the sardine paste to the egg mixture and mix thoroughly.

Assemble

Spread the mixture on thin slices of bread.
Cut the sandwiches into inch‑wide strips.

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).
Egg + breadtop 13% of all pairs

Smell alikemoderate

Cooked together22,662 recipes

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

Smell alikemoderate

Cooked together20,964 recipes

Shared aroma: 2-nonenal (fatty, green).
Egg + lemontop 19% of all pairs

Smell alikelow

Cooked together44,316 recipes

Shared aroma: (e,e)-2,4-decadienal (fatty, deep fried).
Lemon + breadtop 20% of all pairs

Smell alikemoderate

Cooked together8,445 recipes

Shared aroma: 2-nonenal (fatty, green).

Egg and lemon barely smell alike, yet cooks put them together in 44,316 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

Sardines: Provide the main savoury flavour and the paste base of the filling.
Hard boiled egg yolks: Mashed into a creamy base that binds and softens the sardine paste.
Lemon juice: Adds acidity that brightens the rich fish and egg flavours.

“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.