By Nik, founder of 東歐嚴選｜kefir.link and former chef · Updated 2 November 2026
This is a spring soup in a bowl: sweet peas and green asparagus blended with cauliflower into a smooth, bright green purée. Kefir goes in at the end, off the heat, and gives the soup a light creaminess and a fresh tang against the sweet peas. Serve it with a slice of toasted sourdough for a light lunch.
Why the kefir waits until the pot is off the heat
Cultured milk curdles when a soup gets too hot. Strong heat makes its proteins clump, and the soup turns grainy with small white flecks. Whole-milk yogurt, with about 4% fat, curdles quickly even at a bare simmer, while much richer crème fraîche stays creamy. Kefir is acidic, which makes its proteins even more likely to clump, so let the blended soup cool slightly and stir the kefir in with the pan off the heat. Whole-milk kefir holds up better than low-fat kefir.
Bright green and smooth without cream
Green vegetables keep their colour when the cooking is brief. Long cooking fades their chlorophyll from bright green toward a dull olive or yellow, and acid speeds the change, which is one more reason to add the tangy kefir only after cooking. Frozen peas are as good as fresh here, and often better.
Cooked cauliflower turns very soft, so it blends to a smooth, creamy base without any cream. The woody base of the asparagus is the most common cause of a stringy soup, so trim it well before weighing. For an especially fine texture, press the blended soup through a fine sieve to catch the fibres the stick blender misses.
Hot or chilled, with something to dip
Pea-and-asparagus soup is often served as a light spring lunch or starter, and it can be served warm or cold. Toasted sourdough and a little chopped cilantro suit it well. Keep a few whole peas back for texture and finish each bowl with mint and black pepper, or top it with a poached egg and herbs, or serve it beside toasts spread with goat's cheese.
Sweet pea and asparagus kefir soup
Ingredients
Soup
- 2 tbsp olive oil
- 1 onion Peeled and finely chopped.
- 1–2 garlic cloves Peeled and crushed.
- 500 g cauliflower About one small head; remove the leaves and tough stem, then cut into small pieces.
- 250 g green asparagus Weigh after trimming the woody ends; cut into 2.5 cm pieces.
- 250 g frozen green peas
- 1400 ml vegetable stock
- 250 g plain milk kefir Unsweetened; half a 500 g bottle.
- 1 tsp salt Add to taste; salty stock may need less.
- 1 pinch black pepper To taste.
To serve
- 6 slices of sourdough bread
You will need
- Large saucepan
- Immersion blender
- Knife and chopping board
- Kitchen scale and measuring jug
- Measuring spoon
- Toaster
- Food thermometer
Instructions
- Cook the onion and garlic in the olive oil over medium heat, stirring for about 5 minutes, until the onion is soft.
- Simmer the cauliflower in the stock: bring them to a boil together, then lower the heat and cook for about 10 minutes, until tender.
- Add the peas and asparagus and simmer for about 5 minutes, until cooked through and tender.
- Remove the pan from the heat and let the soup cool slightly.
- Carefully blend the soup until smooth with the immersion blender.
- If you plan to keep some soup, ladle that portion into a container now and set aside its share of the kefir. Stir the remaining kefir into the rest with the pan off the heat, and do not boil it again.
- Season to taste with salt and black pepper, adding the salt gradually and using less if the stock is already salty.
- Toast the sourdough slices.
- Ladle into bowls and serve with the toasted sourdough.
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