Lentil Soup with Dijon Mustard

Green lentil soup sits in the comforting territory between a light broth and a more substantial vegetable stew: simple, savoury and easy to make from store-cupboard ingredients. Here the lentils keep their shape as they simmer with onion, carrot, celery, bay and thyme, giving the broth body without making it heavy. Dijon mustard, stirred in at the end rather than cooked for too long, adds the recognisable French-style sharpness that brightens the earthy lentils and vegetables. Serve it hot with crusty bread for a practical lunch or understated supper, and loosen with a little extra stock when reheating if it thickens as it stands.
Cuisine style French-inspired home cooking
Cooking style One-pot cooking • Meal prep friendly • Freezer-friendly
Time commitment Under 1 hour

Why this recipe works

  • Simple aromatics, deeper flavour: Softening onion, carrot and celery before simmering gives the broth a rounded savoury base.
  • Dijon lifts the broth: Stirring in mustard at the end adds gentle acidity and sharpness without overpowering the lentils.
  • Good for batch cooking: The soup keeps well, freezes in portions and can be loosened with a little stock when reheated.

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Timing notes

  • Let it stand briefly: A short rest off the heat helps the lentils settle and allows the broth to thicken slightly before serving.
  • Serve hot: The mustard tastes best when warmed through gently, so serve the soup hot rather than letting it sit too long after finishing.

Ingredient notes

  • Use green lentils: Green lentils hold their shape better than softer red lentils, giving the soup body and texture.
  • Choose a good Dijon: Dijon mustard is central to the finish, so use one with a clean, sharp flavour rather than a sweet mustard.
  • Fresh or dried thyme: Fresh thyme gives a brighter herbal note, while dried thyme works well if added sparingly.

Texture tips

  • Keep the simmer gentle: A hard boil can split the lentils and make the broth cloudy, so maintain a steady, gentle simmer.
  • Loosen if needed: Lentil soup thickens as it stands; add a little stock when reheating if you prefer a lighter broth.

Make-ahead tips

  • Make in advance: Cool completely, then refrigerate in a sealed container for easy lunches or quick suppers.
  • Freeze in portions: Portion before freezing so the soup defrosts evenly and can be reheated only as needed.
  • Reheat gently: Warm in a saucepan over a low to medium heat, stirring occasionally and adding stock if the soup has thickened.

Equipment you'll need

Ingredients
Instructions
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  1. Heat the olive oil in a large pot over a medium heat. Finely chop the onion, dice the carrot and dice the celery, then add them to the pot with the salt and pepper. Cook for 8 to 10 minutes, stirring, until softened but not browned.
  2. Rinse the lentils in a sieve, then add them to the pot. Add the bay leaves, thyme and vegetable stock, and bring to a gentle simmer. Cook for 30 to 35 minutes, stirring occasionally, until the lentils are tender and the broth tastes rounded.
  3. Fish out the bay leaves and thyme sprigs. Stir in the Dijon mustard and simmer for 2 minutes to let it meld into the soup. Taste and adjust seasoning with a little more salt and pepper if needed, then ladle into bowls and serve hot.
  4. Let the soup stand off the heat for 5 minutes so the lentils settle and the broth thickens slightly. Stir once more before serving.

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Recipe notes

Serving suggestions

This recipe pairs well with:

Crusty bread

Tips

  • Keep the simmer gentle; a hard boil can break down the lentils and make the soup muddy.
  • If the soup thickens too much as it stands, loosen it with a splash of vegetable stock and warm through gently.
  • For anyone who is pregnant, elderly, or immunocompromised, choose a pasteurised Dijon mustard and serve the soup piping hot.

Substitutions

  • Replace Dijon mustard with whole-grain mustard for a milder, more textured finish.
  • Replace fresh thyme with dried thyme for a similar herbal note.

Storage

  • Refrigerate up to 4 days
  • Cool completely, then refrigerate in a sealed container. Reheat in a saucepan over a low to medium heat, stirring and adding a little vegetable stock if needed, until piping hot. Freeze in portions for up to 3 months and defrost overnight in the fridge before reheating.

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Recipe overview

  • Servings: 2 servings
  • Total time: 55min (15min active)
  • Difficulty: Easy
  • Cuisine: French
  • Allergens:
    Celery Mustard
Beginner friendly With serving suggestions One pot Freezer friendly Kid friendly

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