Name: Tomato Relish
Ingredients: two cups sugar; two ounces white mustard seed; one quart vinegar; one package; two cups; six large onions; two green peppers

Why it works: Mustard and onion match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Tomato Relish

Ingredients

Directions

Prepare

Peel tomatoes, chop finely, and drain overnight in a jelly bag.
Chop onions, celery, and green pepper finely.

Bottle

Mix well and bottle.
Seal with paraffin.

Nutrition, whole recipe (rough)

105Calories

2 gProtein

0 gFat

24 gCarbs

Counts 5 of 6 ingredients. The other 1 aren't in our nutrition table and add nothing above, so the real totals are higher.

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
White Mustard	1 tsp (5g) yellow	3
Vinegar	1 tbsp (15ml) distilled	3
Seed	not in our table	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 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. See the original page.

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.

Mustard + oniontop 6% of all pairs

Smell alikestrong

Cooked together9,259 recipes

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

Smell alikemoderate

Cooked together14,067 recipes

Shared aroma: isobutyraldehyde (malty, green).
Mustard + peppertop 9% of all pairs

Smell alikemoderate

Cooked together15,430 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + peppertop 11% of all pairs

Smell alikemoderate

Cooked together68,474 recipes

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

Smell alikemoderate

Cooked together18,226 recipes

Shared aroma: acetic acid (sour, vinegar).

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

What each ingredient does

Tomatoes (in the method): Provide the main body and moisture of the relish, which draining concentrates by removing excess liquid.
Sugar: Adds sweetness and helps preserve the relish along with the vinegar.
Vinegar: Adds acidity that gives the relish its tang and helps keep it preserved.
White mustard seed: Adds a sharp, pungent flavour that gives the relish its character.
Onions: Add pungency and savoury body that softens and sweetens as the relish sits.