Name: Pepper Onion Relish
Ingredients: 8 large white onions chopped; 5 sweet red peppers chopped; 5 green peppers chopped; 1 cup sugar; 1 quart white vinegar; 4 teaspoons salt

Why it works: Onion and pepper 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 Onion Relish

Timeabout 45 minutes

Ingredients

Directions

Make the relish

Combine all ingredients and cook until slightly thickened (about 45 minutes), stirring occasionally.

Jar and store

Pack into jars and seal.
Store in refrigerator.

Nutrition, whole recipe (rough)

102Calories

1 gProtein

0 gFat

24 gCarbs

What these numbers assume: 5 portions

Ingredient	Portion assumed	kcal
Sugar	1 tbsp (12.5g) granulated	49
Onion	1 medium (110g)	44
Pepper	1 tsp ground (2.3g)	6
Vinegar	1 tbsp (15ml) distilled	3
Salt	1 tsp (6g)	0

One typical portion per ingredient; the recipe's quantities are not counted. A rough guide only, not for medical or dietary planning.

Recipe from the Recipes Wiki (Fandom).

Steps grouped into stages for easier reading; the method is the source's own.

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.

Onion + peppertop 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

White onions: Provide the bulk of the relish and sweetness as they soften and cook down.
Sweet red peppers: Add colour, sweetness and body as they soften during cooking.
Green peppers: Add a fresher, slightly bitter note and body as they soften during cooking.
Sugar: Adds sweetness and helps balance the sharpness of the vinegar.
White vinegar: Adds acidity that gives the relish its tangy flavour and helps preserve it.

The step that matters

Cooking until slightly thickened. Cooking drives off excess water and concentrates the vegetables and sugar. Stopping too early leaves the relish thin and watery, while cooking too long makes it dry and overly thick.

Swap the onion

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

Capsicumfits better
Mustardfits better
Cabbagefits better
Onionthe original

Fit is the average pairing score against pepper, sugar, vinegar. 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.

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Pepper Onion Relish