Three Onion Soup
Peer reviewed by UK recipe editorsAuthored by UK recipe editorsOriginally published 17 Jan 2026
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This aromatic three onion soup is a sophisticated take on a comforting classic, combining the distinct flavours of leeks, shallots and traditional onions. By slowly caramelising the vegetables until golden and deglazing the pan, you create a deep, savoury base that is naturally sweet and satisfying. The addition of diced potatoes provides a velvety body without the need for thickeners, making it an excellent choice for those seeking a lighter, homemade meal.
As a dairy-free dish that can easily be adapted for vegetarians using vegetable stock, this versatile soup fits perfectly into a healthy weekday routine. The final garnish of sharp balsamic vinegar and a sprinkle of Gruyère adds a professional touch, balancing the earthy notes of the onion broth. Serve it with a slice of crusty sourdough for a nutritious and warming lunch.
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Ingredients for Three Onion Soup
4 medium leeks
1 teaspoon olive oil
1 small onion (110g ), thinly sliced
2 large shallots (110g ), thinly sliced
350ml water
1 large boiling potato (170g) such as Yukon Gold
240ml nonfat chicken broth
120ml grated Gruyère (60g)
2 teaspoons balsamic vinegar
How to make Three Onion Soup
Chop enough white and pale green parts of leeks to measure 475ml . Wash leeks well in a bowl of cold water. Lift from water and drain in a colander. Heat oil in a 10-inch nonstick skillet over moderate heat until hot but not smoking, then cook chopped leeks, onion, and shallots with salt and pepper to taste, stirring frequently, until edges are golden brown, about 15 minutes. Add 120ml water and deglaze skillet, scraping up brown bits. Transfer mixture to a saucepan.
Peel potato and cut into 1/2-inch cubes. Add potato, broth, and remaining cup water to onions. Simmer, covered, stirring occasionally, until potatoes are very tender.
Puré;e 1‚ cups soup in a blender (use caution when blending hot liquids) and stir into remaining soup. Season with salt and pepper.
Serve soup sprinkled with cheese and drizzled with vinegar.
Disclaimer
While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.
Article history
The information on this page is peer reviewed by qualified clinicians.
17 Jan 2026 | Originally published
Authored by:
UK recipe editors
Peer reviewed by
UK recipe editors

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