Why it works: Onion and shallot match in chemistry and in kitchens. They rank in the top 8% of all ingredient pairs, and cooks put them together in 2,431 recipes. Both carry 2,4-decadienal, which smells seaweed. The science ↓
Cu Kieu
Ingredients
Directions
Prepare
Dry the onions under the sun for half a day (or in a very low‑temperature oven for 1½ hours) until semi‑dry.
Boil the vinegar, sugar and salt; allow to cool.
Pickle and store
Pour liquid into the jar to cover the onions.
Marinate for 3 days.
Will last for 2–3 weeks refrigerated.
Nutrition, whole recipe (rough)
What these numbers assume: 4 portions
| Ingredient | Portion assumed | kcal |
|---|---|---|
| Sugar | 1 tbsp (12.5g) granulated | 49 |
| Onion | 1 medium (110g) | 44 |
| Vinegar | 1 tbsp (15ml) distilled | 3 |
| Salt | 1 tsp (6g) | 0 |
One typical portion per ingredient; the recipe's quantities are not counted. A rough guide only, not for medical or dietary planning.
Steps grouped into stages for easier reading; the method is the source's own.
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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Onion + shallottop 8% of all pairsSmell alikestrongCooked together2,431 recipes
Shared aroma: 2,4-decadienal (seaweed).
-
Vinegar + shallottop 12% of all pairsSmell alikemoderateCooked together2,374 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Onion + vinegartop 14% of all pairsSmell alikemoderateCooked together18,226 recipes
Shared aroma: acetic acid (sour, vinegar).
-
Vinegar + sugartop 15% of all pairsSmell alikemoderateCooked together20,806 recipes
Shared aroma: beta-damascenone (apple, rose).
-
Sugar + shallottop 28% of all pairsSmell alikelowCooked together817 recipes
Shared aroma: 1-penten-3-one (fish, pungent).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Spring onions
- Form the main body of the pickle, becoming tender and absorbing the brine as they marinate.
- Vinegar
- Provides the acidity that preserves the onions and gives the pickle its sharp flavour.
- Palm sugar
- Balances the sharpness of the vinegar with sweetness and rounds out the flavour.
- Shallots
- Add a mild, sharp aromatic note that deepens the pickle's flavour.
The step that matters
Drying the onions to semi-dry. Removing surface moisture before brining helps the onions stay crisp rather than watery and lets the vinegar solution penetrate and season them evenly rather than being diluted by excess water.
Swap the onion
How well each one fits the dish's main ingredients (vinegar, sugar, shallot):
- Mustardfits better
- Beetrootfits better
- Chivefits better
- Onionthe original
Fit is the average pairing score against vinegar, sugar, shallot. 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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