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1
Soften the leek and onion
5 Mins
Medium heat, about 160°C (320°F)
Melt the butter in a large pot over medium heat. Add the sliced leek, onion and garlic with a pinch of salt and cook gently for about 5 minutes, stirring often, until soft and sweet-smelling but not browned.
Keep the heat gentle: browned onion turns the soup bitter, and mustard cannot hide it.
Done when: Vegetables are soft, glossy and sweet-smelling, with no browning.
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2
Make the roux and add the stock
5 Mins
Gentle simmer, about 95°C (203°F)
Stir the flour into the softened vegetables and cook for 1 minute, stirring constantly, until it forms a pale paste. Pour in the warm vegetable stock a little at a time, whisking as you go so no lumps form, then bring the soup to a gentle simmer.
Warm stock is the secret to a lump-free roux — cold stock makes the flour seize.
Done when: The soup is smooth, with no lumps, and just beginning to bubble.
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3
Simmer the soup and toast the croutons
10 Mins
Soup at a gentle simmer, about 95°C (203°F); oven at 200°C (400°F)
Turn the heat down and simmer the soup for about 10 minutes until the leek is completely tender and the soup has thickened slightly. While it simmers, toss the bread cubes with the olive oil, spread them on a baking tray, and toast in a hot oven until golden and crisp.
Shake the tray once halfway through so the croutons brown on all sides.
Done when: Leek is fully tender; croutons are golden and crisp all the way through.
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4
Finish with mustard and cream
5 Mins
Off the heat, about 80°C (175°F)
Take the soup off the heat. Stir in the wholegrain mustard and the cream, then season with the salt and pepper and taste. The mustard should be clearly present but not aggressive — add a little more if you like it sharper. Do not let the soup boil once the cream is in, or it may split.
Mustard goes in last because long boiling dulls its flavour; the cream goes in off the heat for the same reason.
Done when: The soup is creamy, pale gold, and tastes clearly of mustard without being sharp.
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5
Serve with croutons on the side
2 Mins
Serving temperature, about 70°C (158°F)
Ladle the soup into warm bowls. Scatter the spring onion over the top and set the bowl of croutons on the table so everyone can add their own — they stay crisp that way. Serve at once with rye bread and Gouda.
Warm the bowls with hot water first — cream soup cools fast in a cold bowl.
Done when: Soup is steaming hot, croutons are crisp, and the spring onion is bright green.
auto_awesome Finishing Touches & Plating
Serve the soup hot, ladled into warm bowls, with the croutons in a small bowl on the side so they stay crisp, and spring onion scattered over the top just before eating.
Netherlands
45m
