Name: Lemon Pickle or Catsup
Ingredients: 6 small lemons; 3 ounces coarse sea salt; 2.5 ounces finely scraped horseradish; 2 ounces shallots or 1.5 ounces garlic; 1.5 pints boiling vinegar; 0.5 ounce bruised ginger; 0.25 ounce whole white pepper; 2 blades of mace

Why it works: Horseradish and shallot 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 ↓

Lemon Pickle or Catsup

Ingredients

Directions

Prepare the lemons

Quarter the lemons and remove any visible seeds, then sprinkle with salt and let sit for a week, turning occasionally.
After a week, place the lemons in a stone jar with their juices.

Add the vinegar and age

In a pot, simmer the vinegar with ginger, white pepper, and mace for 2-3 minutes, then pour it over the lemons.
Seal the jar and let it sit in a warm place for 2-3 months before using, or up to 4-5 months before straining.

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.

Horseradish + shallottop 1% of all pairs

Smell alikestrong

Cooked together376 recipes

Shared aroma: coumarin (sweet, hay).
Lemon + gingertop 5% of all pairs

Smell alikestrong

Cooked together5,154 recipes

Shared aroma: beta-phellandrene (minty, terpene).
Lemon + shallottop 6% of all pairs

Smell alikestrong

Cooked together2,523 recipes

Shared aroma: eucalyptol (eucalyptus, herbal).
Shallot + gingertop 7% of all pairs

Smell alikemoderate

Cooked together565 recipes

Shared aroma: eucalyptol (eucalyptus, herbal).
Lemon + horseradishtop 9% of all pairs

Smell alikestrong

Cooked together1,155 recipes

Shared aroma: coumarin (sweet, hay).

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

What each ingredient does

Lemons: Provide the main sour, aromatic flavor and soften as they cure in salt.
Coarse sea salt: Draws moisture out of the lemons and preserves them during the week of curing.
Boiling vinegar: Acidity that preserves the lemons and carries the spice flavors into the pickle.
Horseradish: Adds a sharp, pungent heat that mellows with long aging.

The step that matters

Sealing the jar and aging it. The long rest in a sealed jar lets salt, acid and spices slowly penetrate the lemon and mellow its harshness. Rushing this stage leaves the pickle sharp and underdeveloped, and an open or poorly sealed jar risks spoilage.

Swap the white pepper

How well each one fits the dish's main ingredients (lemon, horseradish, shallot, vinegar, ginger, mace):

Tarragonfits better
Allspicefits better
Turmericfits better
White pepperthe original

Fit is the average pairing score against lemon, horseradish, shallot, vinegar, ginger, mace. 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.

Lemon Sauce236 recipes

Horseradish Sauce17 recipes

Tomato Soup526 recipes

Brown Bread461 recipes

Like knowing why a recipe works?

The free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.

Prefer an account? Create a free account to save pairings and unlock the full chemistry.

Lemon Pickle or Catsup