Name: Tripe a LA Kilkenny
Ingredients: 1 piece double tripe, cut into square pieces; 2 cow-heels, cut into pieces; 10 large onions, peeled and halved; water; flour; butter; coarse sea salt; mustard

Why it works: Onion and mustard match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Tripe a LA Kilkenny

Ingredients

Directions

Boil the halved onions in water until tender.
Add the tripe and cow-heels to the pot and boil for 10 minutes.
Pour off most of the liquid, then sprinkle in a little flour.
Add butter, coarse sea salt, and mustard, and shake over the heat until the butter melts.
Transfer to a serving dish and serve hot.

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.

Onion + mustardtop 6% of all pairs

Smell alikestrong

Cooked together9,259 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Flour + buttertop 12% of all pairs

Smell alikelow

Cooked together124,287 recipes

Shared aroma: isobutyraldehyde (malty, green).
Flour + mustardtop 13% of all pairs

Smell alikemoderate

Cooked together5,066 recipes

Shared aroma: isobutyraldehyde (malty, green).
Onion + buttertop 15% of all pairs

Smell alikemoderate

Cooked together42,912 recipes

Shared aroma: decanal (soap, orange peel).
Onion + flourtop 17% of all pairs

Smell alikemoderate

Cooked together32,460 recipes

Shared aroma: isobutyraldehyde (malty, green).

Flour and butter barely smell alike, yet cooks put them together in 124,287 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

Tripe: Forms the main body of the stew and becomes tender after boiling.
Cow-heels: Adds gelatin from the connective tissue, giving the stew body and a richer texture.
Onions: Soften during boiling and add sweetness and savoury depth to the broth.
Flour: Lightly thickens the remaining liquid so it clings to the tripe and onions.
Butter: Adds fat and richness, which carries flavour and gives a smooth finish.