Name: Potato and Leek Soup II
Ingredients: 930 g leeks (not including the toughest portion of their green tops), halved lengthwise and sliced; 90 g unsalted butter; 330 g onion , peeled and diced; 600 g yellow potatoes , peeled and diced into 1–2 cm cubes; 2.7 L chicken stock; Salt; Freshly ground black pepper

Why it works: Onion and potato are a kitchen classic. They rank in the top 3% of all ingredient pairs, and cooks put them together in 9,023 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Potato and Leek Soup II

Time10 minutes

Ingredients

930 g leeks (not including the toughest portion of their green tops), halved lengthwise and sliced
90 g unsalted butter
330 g onion , peeled and diced
600 g yellow potatoes , peeled and diced into 1–2 cm cubes
2.7 L chicken stock
Salt
Freshly ground black pepper

Directions

Prepare

Wash the leeks thoroughly in water to remove dirt and grit, then drain.

Make the soup

Melt the butter in a large pot over medium heat. Add the vegetables, and season with a pinch each of salt and pepper. Stir to coat everything well with butter.
Cover the pot, and let the vegetables sweat over low heat for 10 minutes—make sure not to let them brown.
Stir in the chicken stock, and bring the pot to a boil. Simmer until the vegetables are cooked through.

Blend and finish

Working in batches if necessary, purée the mixture using a hand- or full-size blender.
If you would like a very smooth soup, work the puréed mixture through a sieve into a clean pot—this is laborious, but it yields a velvety product.
Taste the soup, and season to taste with additional salt and pepper.

Nutrition, whole recipe (rough)

478Calories

37 gProtein

15 gFat

48 gCarbs

What these numbers assume: 6 portions

Ingredient	Portion assumed	kcal
Chicken	100g cooked	165
Potato	1 medium (173g) baked	161
Butter	1 tbsp (14g)	102
Onion	1 medium (110g)	44
Black Pepper	1 tsp ground (2.3g)	6
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.

Recipe from the Wikibooks Cookbook.

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.

Onion + potatotop 3% of all pairs

Smell alikemoderate

Cooked together9,023 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Leek + oniontop 4% of all pairs

Smell alikestrong

Cooked together1,326 recipes

Shared aroma: ethyl butyrate (apple, fruity).
Leek + potatotop 6% of all pairs

Smell alikemoderate

Cooked together30 recipes

Shared aroma: 1-octen-3-ol (mushroom, earthy).
Potato + chickentop 7% of all pairs

Smell alikemoderate

Cooked together2,756 recipes

Shared aroma: (z)-4-decenal (green, must).
Onion + chickentop 8% of all pairs

Smell alikemoderate

Cooked together17,814 recipes

Shared aroma: gamma-nonanolactone (coconut, sweet).

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

What each ingredient does

Leeks: Softens into sweet, mild body that gives the soup its base flavour and texture.
Potatoes: Starch thickens the soup and gives it a creamy, body-rich texture when puréed.
Butter: Fat carries flavour and helps the vegetables soften gently in the pot.
Onion: Adds savoury sweetness and aroma as it softens into the base.
Chicken stock: Liquid that cooks the vegetables and forms the body of the soup.

The step that matters

Sweating the vegetables without browning. Keeping the vegetables pale over low heat lets them soften and release sweetness gently. Browning would add roasted, bitter notes that change the soup's clean, mild flavour.

Swap the leek

How well each one fits the dish's main ingredients (butter, onion, potato, chicken, pepper):

Capsicumfits about as well
Chivefits about as well
Leekthe original
Tomatofits about as well

Fit is the average pairing score against butter, onion, potato, chicken, 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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Potato and Leek Soup II