Spring Onion Soup
This creamy spring onion soup is a smooth, vibrant green soup built from scallions, a sweet onion, and potatoes, blended until silky and ready in about 25 minutes. It tastes light and fresh but still comforting, which makes it a perfect way to use up a big bunch of spring onions while they are in season. If you love a gentle onion flavor without anything sharp or overpowering, this is the bowl to make.
I am absolutely crazy about onions, yet somehow I had never eaten onion soup until I made this one. The recipe came out of necessity: I went to Costin’s parents’ house and came back with about 10 kilos of cherries, huge bunches of parsley and dill, lots of leafy greens, and a bag full of extra-large scallions. I had no idea what to do with so many of them. Baked scallions were out (I had eaten those almost every day for weeks), and working through them in salads would have taken forever. You know that I love creamy soups, so this recipe turned out to be just perfect for me.
What goes into this scallion soup
The ingredient list is short, so each one earns its place. Here is what each part does:
- Spring onions (scallions): the star of the soup. Eight of them give the whole pot its fresh green color and that subtle, sweet onion flavor. Use the white and the green parts both, since the green tops are what tint the soup that lovely spring shade.
- One regular onion: this adds a deeper, rounder onion base under the brighter scallion flavor, so the soup tastes balanced rather than one-note.
- Two medium potatoes: peeled and cubed, the potatoes are what make this soup creamy without any cream. Their starch is the body of the soup once everything is blended.
- Butter or olive oil: for softening the onions. Two tablespoons of butter give a richer finish; two to three tablespoons of olive oil keep it fully plant-based.
- Seasoning: sea salt, ground white pepper, ground coriander, and fresh thyme. The white pepper and coriander are gentle and warm, so they support the onion instead of fighting it.
Tips for getting it right
The whole soup depends on one step: cooking the onions slowly. Keep the heat low and stir the chopped spring onions and onion almost continuously. You want them soft and sweet, not browned, so be careful not to burn them. This takes up to 10 to 15 minutes, and if they start to stick, just add a little splash of water to keep things moving. Burnt onion will turn the soup bitter and muddy the color, so patience here is what gives you that clean, sweet flavor and the bright green look.
Boil the potatoes separately in just enough water to cover them, then add them to the onion pot along with their cooking water. That starchy water is part of the soup, so do not pour it out. When you blend, I recommend using an immersion blender, which makes it easy to blend the soup right in the pot with no transferring back and forth. Add more water a little at a time until the soup reaches the creamy consistency you like.
How to make it vegan
As written, this soup is vegetarian because of the butter, but it switches to vegan with one swap: use two to three tablespoons of olive oil instead of the butter to soften the onions. Nothing else changes, and because the creaminess comes entirely from the blended potatoes rather than dairy, the texture stays just as smooth. Finish with a drizzle of olive oil on top either way, which adds a little richness and a glossy look.
What to serve with it
This is a light soup, so it loves a bit of texture alongside. A piece of crusty bread or a few croutons are the simplest pairing. If you want to make a fuller meal of it, serve it as a starter before something heartier like my creamy polenta with tofu and pepper sauté. And if cooking the scallions down made you curious about other ways to use them, my baked scallions with za’atar are a great companion side. Lovers of blended soups will also want to bookmark my cream of potato and carrot soup, which uses the same no-cream, blend-it-smooth approach.
Storing and making it ahead
This soup keeps well in an airtight container in the fridge for three to four days, and it actually tastes lovely cold or gently reheated. Warm it slowly on the stove and stir in a splash of water if it has thickened in the fridge, since the potato starch firms up once chilled. It also freezes fine for up to two to three months; thaw in the fridge overnight, then reheat and give it a quick blend or whisk to bring the creamy texture back together. If you are into easy blended soups like this, you might also enjoy my creamy carrot and ginger soup or my cream of broccoli soup for your weekly rotation.
I really hope you love this creamy spring onion soup as much as I do. If you make it, please rate the recipe below and leave a comment telling me whether you went with butter or olive oil, and how green your soup turned out. I would love to hear how it came together for you!
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Spring Onion Soup
Ingredients
- 8 spring onions chopped
- 1 onion chopped
- 2 medium potatoes peeled and cubed
- 2 Tbsp butter or 2-3 Tbsp olive oil
- sea salt to taste
- ½ tsp white pepper ground
- ⅓ tsp coriander ground
- fresh thyme
Instructions
- Boil the potatoes in a small pot, adding just enough water to cover them.
- In a separate pot, add the butter or olive oil and let it melt and heat over low heat.
- Add the chopped spring onions and onion. Stir continuously until all the onions are soft and cooked, being careful not to burn them. This will take up to 10-15 minutes.
- If they start to stick, add a little water.
- When the potatoes are boiled, add them to the pot with the onions, along with their cooking water.
- Stir and season with salt, white pepper and ground coriander.
- Remove from the heat.
- Using an immersion blender, blend all the vegetables until the soup reaches a creamy consistency.
- If needed, add more water to reach the desired consistency.
- Serve topped with fresh thyme and a drizzle of olive oil.
Notes
Frequently Asked Questions
As written it is vegetarian, because it uses 2 tablespoons of butter to soften the onions. To make it fully vegan, just swap the butter for 2 to 3 tablespoons of olive oil. The creaminess comes from blended potatoes, not dairy, so the texture stays smooth either way.
The two medium potatoes do all the work. Once they are boiled and blended into the soup, their starch gives it a thick, smooth, creamy body with no milk or cream needed. Adjust the consistency by blending in more water a little at a time.
Use both the white and the green parts. The white parts add sweetness and onion depth, while the green tops are what give the soup its vibrant spring-green color. Using only the greens would lighten the flavor and the look.
Cooking the spring onions and onion slowly over low heat keeps them sweet and tender instead of browned. Burnt onion turns the soup bitter and muddies that bright green color, so stir almost continuously and add a splash of water if they start to stick. This step takes up to 10 to 15 minutes.
Store it in an airtight container in the fridge for three to four days. It also freezes well for two to three months. Reheat gently on the stove and stir in a little water to loosen it, since the potato starch thickens the soup once it is chilled.
Because it is a light soup, it pairs well with crusty bread or croutons for texture. Serve it as a starter before a heartier dish, or alongside baked scallions if you have extra spring onions to use up. A final drizzle of olive oil on top adds a little richness.
This soup is so amazing! My favorite thing about it is it’s ready in no time. And my daughter loves it too, and she’s a very picky eater!
Thank you for sharing, Ruxandra! I love your blog!
You’re welcome! Happy to hear you liked the recipe!