This vegan onion and leek soup begins with the slowly caramelised onions, building natural sweetness and depth before the leeks go into the pot. Finished with some vegan cream for a velvety texture, the result is a smooth, lighter soup that is a perfect starter - comforting but never heavy. It uses simple ingredients and is easy to adapt: Enjoy it on its own with some cheesy bread, or add your favourite protein to turn it into something more substantial.
Why You'll Love This Onion and Leek Soup
- Caramelised for extra flavour - by slowly caramelising the onions, their natural sweetness and depth of flavour are emphasised.
- Naturally vegan - plant-based ingredients but still flavourful and satisfying.
- Smooth and refined - ideal as a starter or dinner party first course.
- Lighter but nourishing - comforting, yet gentle on the stomach.
- Budget-friendly ingredients - only a few ingredients. Onion and leeks go a long way!
- A base for something more substantial - Add your favourite protein, such as cheese or butterbeans if you are vegetarian, or some oily fish or chicken.
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Key Ingredients and Notes
- Leek and White Onion - Leek and white onion complement each other very well, providing a balanced flavour base to the soup. The white onion gives flavour depth. Caramelising replaces the sharpness of the raw onion with concentrated sweetness, and the leek balances with a milder sweetness. Together, creating a not-too-mild but not-too-pungent soup.
- Vegetable stock - adds more layers of flavour. I make my own vegetable stock; it is very easy.
- Dairy-free cream - adds a velvety texture to the soup and provides a little bit of body. It is optional, though, as the caramelised onion and leek blend to a silky smooth texture.
- Olive oil - I use it for its fruity, rich flavour and its health benefits compared to other oils.
- Bay leaf and peppercorns - supporting flavours to add depth to the soup without overpowering the main ingredients.
See the recipe card for quantities.
How to Make Onion and Leek Soup
- Peel and top-and-tail the onions. Slice evenly, no thicker than the thickness of a coin.
- Cut the leeks in half lengthwise and chop off the green leaves, leaving only the white and light green parts.
- Cut the leeks in half lengthwise and wash thoroughly between the layers.
- Cut the leek evenly and not too thick.
- Heat the olive oil in a pot and add the bay leaf and peppercorns.
- Cook the onions on a gentle heat until they caramelise - they turn golden brown. The onion may start to burn on the bottom of the pot. Just add a little of the stock if it does.
- Add the leek and salt and sautรฉ until soft.
- Pour in the vegetable stock and bring to a boil. Once boiling, reduce to a simmer and cook uncovered for 10 minutes.
- Puree the soup.
- Return the pureed soup to the pot and heat over a medium heat.
- Stir in the dairy-free cream.
- Optionally, served garnished with a swirl of dairy-free cream and pesto.
Ingredient Variations and Additions
This recipe is for a simple onion and leek soup, and it is an excellent base from which to be creative. You may add spices like fennel or herbs like tarragon, parsley, thyme or oregano to add more flavour layers. If you want to add more heat, you can use fresh jalapeรฑos or serranos. If you choose to add anything, add it after you have sautรฉed your leeks, then blend it with the other ingredients.
You can bulk out the soup by adding roasted beans (chickpeas, butterbeans) and vegetables like broccoli or cauliflower. Just add them after blending.
In the FAQs section, I detail some proteins you can add, depending on your dietary preferences, to make the soup more substantial.
Equipment
As this is a blended soup, you will need either an electric jug blender or an electric stick blender.
Storage
Store refrigerated for up to 3 days.
This onion and leek soup can be batch-cooked and frozen for up to 3 months.
Chef's Tips
Here are a few tips to help you achieve the best results with this onion and leek soup recipe:
- Take time to wash the leek thoroughly to avoid any grit hiding in its leaves.
- Don't be tempted to use the darker green leaves of the leek, as they can make the soup bitter and stringy. Only use the white and light green parts of the leek.
- Be sure to slow-cook the onions on a gentle heat to achieve the best caramelisation. Chop as I have shown so that they caramelise easily. If you notice the onions sticking to the bottom of the pot, add a little stock to prevent sticking.
FAQ
Yes - leave out the dairy-free cream. The caramelised onion and leek still give the soup a silky texture when blended, and the caramelisation ensures it won't taste flat.
Strictly, no; however, caramelisation of the onions definitely adds to the flavour profile, bringing sweetness. If you skip caramelising the onion, then the taste will be lighter and more onion-forward. Caramelising the onion helps to create flavour balance with the leek.
Yes. This recipe is suitable for batch cooking and freezing. Let the soup cool completely, then pour it into appropriately sized containers for one serving each. Defrost overnight and gently reheat.
Vegan: Add beans such as butter beans or haricot beans. Another great addition is seeds like hemp seeds or pumpkin seeds. You could also stir in a portion of cooked red lentils. Another option is to blend in silken tofu.
Vegetarian: All the above plus Greek yoghurt, or feta cheese. Try blended cottage cheese - it'll add creaminess and protein without an overpowering flavour.
Meat and fish: Add shredded roast chicken, tinned mackerel, smoked salmon or even turkey.
It's naturally plant-based and full of vegetables. Feel free to omit the vegan cream if you want to. The wonderful thing about this recipe is that it can serve as a base from which you can add even more nutrition, such as protein. You are in control of what you add, be it beans, pulses, cheese, rice, fish or meat!
Related Recipes
Looking for more soup recipe ideas? Try these:
- Dairy Free Beetroot Soup with Sauerkraut
- Winter Vegetable Soup. Warming and Nourishing.
- Cannellini Bean and Cavolo Nero Soup. Simple and Healthy
- Mulligatawny, Easy One Pot Lentil And Apple Soup
- Easy One-Pot Miso Tahini Noodle Soup With Wild Greens
- Simple Asian Roasted Pumpkin And Coconut Soup
- Easy One Pot Curried Parsnip Soup
- The Best Sheet Pan Carrot and Red Pepper Soup
๐ Recipe
Vegan Onion and Leek Soup with Caramelised Onions
Equipment
- Digital scales
- Blender
Ingredients
- 450 g Leek
- 450 g White onions
- 2 Bay leaf
- 4 tablespoon Olive Oil
- 10 Black peppercorns
- 2 teaspoon Salt
- 1 l Vegetable stock
- 250 ml Dairy-free cream
Instructions
- Top and tail the onions and peel. Slice the onions evenly - no thicker than a coin.
- Cut the leeks lengthwise and rinse between layers to remove any grit/dirt. Pat dry.
- Slice the leek - the white and light green part only. Slice evenly and not too thick. Set aside the dark green bits of the leek for vegetable stock.
- In a pot, heat olive oil, add the bay leaf and peppercorns. Over a gentle heat, caramelise the onions until they are golden brown.
- Once the onions are ready, add the leek and salt and sautรฉ until the leek is soft.
- Add the vegetable stock, cover, and bring to a boil. When it comes to a boil, simmer, uncovered, for ten minutes.
- Puree the soup.
- Bring the soup back to the stove and stir in the cream over medium heat. Serve hot. You can serve it garnished with a swirl of vegan cream, or a swirl of pesto, or a sprinkling of seeds.
Nutrition
NOTES
Food Safety
- Wash your hands regularly while preparing, handling and cooking food.
- Wipe down countertops and high-contact points regularly.
- If you cook meat and fish, do not use the same utensils on cooked food that previously touched raw meat. Use separate chopping boards for meat and fish. Wash your chopping boards immediately after use.
- Thoroughly cook food to a minimum temperature of 165 ยฐF (74 ยฐC).
- Don't leave food at room temperature for extended periods (more than 2 hours).
- Store food correctly.
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