Name: Pepper Hash
Ingredients: 12 red sweet peppers; 12 green peppers; 3 tablespoons coarse sea salt; 2 cups white or dark sugar; 12 white onions; 2 cups vinegar; 3 red hot peppers

Why it works: Pepper and onion are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Pepper Hash

Ingredients

Directions

Prepare the vegetables

Grind the red sweet peppers, green peppers, and white onions finely.
Place the ground mixture in a kettle.
Pour boiling water over the mixture, then drain immediately.

Cook and seal

Add the coarse sea salt, sugar, and vinegar to the kettle.
Boil for 15 minutes.
Seal the mixture airtight.

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 + oniontop 11% of all pairs

Smell alikemoderate

Cooked together68,474 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + vinegartop 14% of all pairs

Smell alikemoderate

Cooked together18,226 recipes

Shared aroma: acetic acid (sour, vinegar).
Pepper + vinegartop 14% of all pairs

Smell alikemoderate

Cooked together27,814 recipes

Shared aroma: 4'-methylacetophenone (bitter almond).
Sugar + vinegartop 15% of all pairs

Smell alikemoderate

Cooked together20,806 recipes

Shared aroma: beta-damascenone (apple, rose).
Pepper + sugartop 32% of all pairs

Smell alikelow

Cooked together19,401 recipes

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

Pepper and sugar barely smell alike, yet cooks put them together in 19,401 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

Sugar: Adds sweetness and helps preserve the mixture, balancing the vinegar's sharpness.
Vinegar: Adds acidity that gives the relish its tang and helps keep it preserved.
White onions: Adds bulk and a sharp, savory flavor to the chopped mixture.