Name: Pepper Relish
Ingredients: 1 dozen green peppers; 1½ cups sugar; 1 dozen red peppers; 3 tablespoons salt; 16 good-sized onions; 1 bunch celery; 3 pints vinegar; 2 tablespoons white mustard seed

Why it works: Celery and mustard are a kitchen classic. They rank in the top 2% of all ingredient pairs, and cooks put them together in 4,169 recipes. Both carry guaiacol, which smells smoky, sweet. The science ↓

Pepper Relish

Ingredients

Directions

Prepare the vegetables

Chop the green and red peppers, onions, and celery finely.
Cover the chopped ingredients with boiling water and let them stand for 5 minutes, then drain.

Cook and can

In a pot, combine the drained ingredients with vinegar, sugar, and salt.
Boil the mixture for 30 minutes.
Can the relish while it is still hot.

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.

Celery + mustardtop 2% of all pairs

Smell alikemoderate

Cooked together4,169 recipes

Shared aroma: guaiacol (smoky, sweet).
Pepper + celerytop 5% of all pairs

Smell alikestrong

Cooked together16,012 recipes

Shared aroma: 4'-methylacetophenone (bitter almond).
Onion + mustardtop 6% of all pairs

Smell alikestrong

Cooked together9,259 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + celerytop 7% of all pairs

Smell alikemoderate

Cooked together18,518 recipes

Shared aroma: guaiacol (smoky, sweet).
Vinegar + mustardtop 7% of all pairs

Smell alikemoderate

Cooked together14,067 recipes

Shared aroma: isobutyraldehyde (malty, green).

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

What each ingredient does

Vinegar: Provides the acidity that gives the relish its tang and helps preserve it.
Sugar: Adds sweetness that balances the sharpness of the vinegar.
White mustard seed: Adds a sharp, pungent flavor to the relish.

Swap the onion

How well each one fits the dish's main ingredients (pepper, sugar, celery, vinegar, mustard):

Horseradishfits better
Capsicumfits better
Lettucefits better
Onionthe original

Fit is the average pairing score against pepper, sugar, celery, vinegar, mustard. Candidates are from the same food group and used in at least 100 recipes.

“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.