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 ↓
Tomato Catsup
two bottlesIngredients
Directions
Prepare the tomatoes
Gather a peck of tomatoes, pick out the stems, and wash them.
Put them on the fire without water, sprinkle a few spoonfuls of salt, and let them boil steadily for an hour, stirring frequently.
Strain the tomatoes through a colander, then through a sieve.
Season and reduce
Put the liquid on the fire with half a pint of chopped onions and half a quarter of an ounce of mace broken into small pieces.
If not sufficiently salted, add a little more salt and one tablespoonful of whole black pepper.
Boil all together until just enough to fill two bottles.
Bottle
Cork the bottles tightly.
Make it in August, in dry weather.
Nutrition, whole recipe (rough)
Counts 3 of 4 ingredients. The other 1 aren't in our nutrition table and add nothing above, so the real totals are higher.
What these numbers assume: 3 portions
| Ingredient | Portion assumed | kcal |
|---|---|---|
| Onion | 1 medium (110g) | 44 |
| Black Pepper | 1 tsp ground (2.3g) | 6 |
| Salt | 1 tsp (6g) | 0 |
| Mace | 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.
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.
-
Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Mace + peppertop 16% of all pairsSmell alikelowCooked together12,257 recipes
Shared aroma: myristicin (spice, warm).
-
Onion + macetop 17% of all pairsSmell alikelowCooked together7,078 recipes
Shared aroma: eugenol (clove, spicy).
Mace and pepper barely smell alike, yet cooks put them together in 12,257 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
- Tomatoes (in the method)
- Provides the main body, acidity and liquid that reduces into a thick sauce.
- Onions
- Adds savoury depth and body to the sauce as it cooks down.
- Mace
- Adds a warm, aromatic flavour to the ketchup.
- Black pepper
- Adds a sharp, aromatic bite that balances the sweetness of the tomatoes.
The step that matters
Boiling the tomatoes without water. Tomatoes with no added liquid can scorch on the bottom of the pan. Stirring frequently spreads the heat evenly and keeps the pulp from sticking and burning during the hour-long boil.
Swap the mace
How well each one fits the dish's main ingredients (onion, pepper):
- Garlicfits better
- Thymefits better
- Parsleyfits better
- Macethe original
Fit is the average pairing score against onion, pepper. 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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