Name: White Onion Sauce
Ingredients: 6 large firm onions; 1 tablespoon coarse sea salt; 1 tablespoon butter; 1 ladle good consomme; 2 tablespoons plain sauce; ½ pint good boiled cream

Why it works: Butter and cream are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 41,516 recipes. Both carry delta-dodecalactone, which smells sweet, creamy. The science ↓

White Onion Sauce

Ingredients

Directions

Prepare the onions

Peel and cut the onions in half in a basin of water.
Boil water in a large stewpan and add the onions with salt.
When half boiled, drain the onions and place them in another pot of boiling water until very tender.

Make the sauce

Drain again and place the onions in a stewpan with butter, stirring until well mixed.
Stir in the consomme and boil for a few minutes.
Add the plain sauce and stir until well boiled.
Rub the mixture through a fine sieve, adding the boiled cream.
Season with salt and heat until very hot before serving.

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.

Butter + creamtop 8% of all pairs

Smell alikemoderate

Cooked together41,516 recipes

Shared aroma: delta-dodecalactone (sweet, creamy).
Sauce + creamtop 9% of all pairs

Smell alikemoderate

Cooked together4,787 recipes

Shared aroma: ethanol (alcoholic, ethereal).
Butter + saucetop 15% of all pairs

Smell alikelow

Cooked together15,338 recipes

Shared aroma: ethanol (alcoholic, ethereal).
Onion + buttertop 15% of all pairs

Smell alikemoderate

Cooked together42,912 recipes

Shared aroma: decanal (soap, orange peel).
Onion + creamtop 18% of all pairs

Smell alikelow

Cooked together10,827 recipes

Shared aroma: 2-nonanone (fruity, floral).

Butter and sauce barely smell alike, yet cooks put them together in 15,338 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

Onions: Form the bulk of the sauce, and their sugars soften and sweeten as they cook until very tender.
Butter: Adds fat and richness, carrying flavour as the onions cook gently in it.
Consomme: Contributes savoury, meaty depth to the onions as it boils down briefly.
Plain sauce: Thickens the mixture so it coats the back of a spoon after boiling.
Boiled cream: Adds moisture and smoothness, giving the sieved sauce a silky, rich texture.

The step that matters

Rubbing the mixture through a fine sieve. The onions must be very tender before sieving, or the purée will be grainy and fibrous. Passing the hot mixture through a fine sieve removes remaining fibres and skins, producing a smooth sauce. Adding the cream after sieving keeps it from being overworked or split by the heat.