Why it works: Shallot and horseradish match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 376 recipes. Both carry coumarin, which smells sweet, hay. The science ↓
Mushroom Catsup
Ingredients
Directions
Salt the mushrooms
Layer mushrooms in a deep earthen pan, sprinkling each layer with coarse sea salt.
Let sit for 2-3 hours for the salt to penetrate.
Wash the mushrooms by hand.
Stir the mushrooms daily for 2 days.
Make the ketchup
Transfer to a stone jar.
Add 1 ounce of whole black pepper for each quart of mushrooms.
Seal the jar.
Place the jar in a pot of boiling water.
Boil for 3 hours.
Remove the jar.
Strain the juice through a fine sieve into a clean pot.
Gently boil the juice for 30-60 minutes, skimming off any foam.
Pour the juice into a dry jar, cover, and let it sit in a cool place for 12 hours.
Season and bottle
Carefully pour the juice back into a pot and add 4 ounces of shallots, 2 cloves of garlic, and grated horseradish.
Boil slowly for another hour.
Skim well.
Once cooled, bottle and cork tightly.
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.
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Shallot + horseradishtop 1% of all pairsSmell alikestrongCooked together376 recipes
Shared aroma: coumarin (sweet, hay).
-
Mushroom + shallottop 4% of all pairsSmell alikemoderateCooked together1,982 recipes
Shared aroma: 2,4-decadienal (seaweed).
-
Shallot + garlictop 4% of all pairsSmell alikestrongCooked together2,000 recipes
Shared aroma: coumarin (sweet, hay).
-
Pepper + clovetop 5% of all pairsSmell alikestrongCooked together17,451 recipes
Shared aroma: ethyl octanoate (fruity, wine).
-
Shallot + clovetop 5% of all pairsSmell alikestrongCooked together1,677 recipes
Shared aroma: eucalyptol (eucalyptus, herbal).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Fresh mushrooms
- Provide the main body and savory flavor of the ketchup as they break down into juice.
- Coarse sea salt
- Draws moisture out of the mushrooms and preserves the juice by inhibiting spoilage.
- Whole black pepper
- Adds warm, pungent spice that infuses the juice during the long boil.
- Shallots
- Add mild onion-like sharpness and aromatic depth to the cooked juice.
- Garlic
- Contributes pungent aroma and savory depth to the finished ketchup.
- Grated horseradish
- Adds sharp, pungent heat that lingers after the juice is cooked.
The step that matters
Skimming the juice during the boils. Foam and impurities rise to the surface as the juice simmers. Removing them keeps the ketchup clear and clean-tasting instead of murky or bitter.
Swap the clove
How well each one fits the dish's main ingredients (mushroom, pepper, shallot, garlic, horseradish):
- Capersfits better
- Thymefits better
- Parsleyfits better
- Clovethe original
Fit is the average pairing score against mushroom, pepper, shallot, garlic, horseradish. 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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