Name: Cold Catsup
Ingredients: ½ peck ripe tomatoes, peeled and finely chopped; 1 cup grated horseradish; 1 cup salt; 1 cup mixed brown and white mustard seed; 2 tablespoons ground black pepper; 2 red peppers, seeded and finely chopped; 1 ounce celery seed; 1 cup chopped onions; 1 teaspoon ground cloves; 1 teaspoon ground mace; 2 teaspoons cinnamon; 1 cup brown sugar; 1 quart best cider vinegar

Why it works: Horseradish and mustard match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 1,832 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

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.

Horseradish + mustardtop 1% of all pairs

Smell alikestrong

Cooked together1,832 recipes

Shared aroma: coumarin (sweet, hay).
Mustard + celerytop 2% of all pairs

Smell alikemoderate

Cooked together4,169 recipes

Shared aroma: guaiacol (smoky, sweet).
Tomato + celerytop 4% of all pairs

Smell alikemoderate

Cooked together3,377 recipes

Shared aroma: 4'-methylacetophenone (bitter almond).
Pepper + clovetop 5% of all pairs

Smell alikestrong

Cooked together17,451 recipes

Shared aroma: ethyl octanoate (fruity, wine).
Pepper + celerytop 5% of all pairs

Smell alikestrong

Cooked together16,012 recipes

Shared aroma: 4'-methylacetophenone (bitter almond).

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

What each ingredient does

Ripe tomatoes: Forms the bulk of the relish and gives it body and moisture.
Cider vinegar: Adds acidity that sharpens the flavour and helps preserve the relish.
Brown sugar: Adds sweetness that balances the sharpness of the vinegar and spices.
Grated horseradish: Contributes a sharp, pungent heat.
Mustard seed: Adds a sharp, mustardy bite and a textural note.
Chopped onions: Adds savoury depth and aromatic sharpness to the blend.

The step that matters

Mix without boiling. Heating would soften the fresh tomato and onion flavour and blunt the sharp horseradish and mustard. Thorough mixing spreads the salt, sugar and acid evenly through the chopped vegetables.

Swap the mace

How well each one fits the dish's main ingredients (tomato, horseradish, mustard, pepper, celery, onion, clove):

Thymefits better
Capersfits better
Tarragonfits better
Macethe original

Fit is the average pairing score against tomato, horseradish, mustard, pepper, celery, onion, clove. 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.

Cold Catsup

Cold Catsup

Ingredients

Directions

Mix

Store and serve