Vegetable soup made in the Thermomix® turns creamy without any cream, as long as you use floury potatoes to bind the stock during blending. This only works if the onion is sweated first for 3 minutes at 120°C, because that is when the natural sweetness develops. Cooking everything together from the start gives a watery, bland result.
We have been making this soup at least once a week for years. The base is always the same: sweat the onion, cook the vegetables, blend. What changes is the vegetable, depending on what the fridge or the season has to offer. Sometimes kohlrabi and carrots as in the recipe card below, sometimes broccoli and cauliflower, sometimes frozen peas straight from the freezer. The principle stays the same.
Vegetable Soup, Thermomix®
Ingredients 0 / 8 ✓
- 1 onion
- 30 g olive oil
- 150 g kohlrabi
- 250 g floury potatoes
- 300 g carrot
- 900 g vegetable stock
- 1/2 tsp white pepper
- 1 stalk leek (optional) small
Instructions 0 / 5
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1
Chop the onion.
Peel the onion, halve it, place in the mixing bowl and chop for 3 sec / speed 5, then push down with the spatula.
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2
Sweat the onion.
Add the oil and sweat for 3 min / 120°C (TM31: Varoma).
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3
Cut the vegetables.
Meanwhile, peel the kohlrabi, potatoes and carrots, cut into pieces and add to the mixing bowl.
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4
Cook the soup.
Add the stock and pepper and cook for 20 min / 100°C / speed 1.
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5
Blend the soup.
Blend for 1 minute, gradually increasing from speed 5 to 10.
Tip: After blending, add a small leek cut into fine rings and cook for a further 3 minutes. The vegetables in the soup can be varied to suit what you have on hand.
Video
Nutrition per serving
Sweating makes the difference
The 3 minutes at 120°C for the onion are not an optional step. Onions contain fructans, complex sugars that break down into fructose (simple sugar) when heated. The perceived sweetness increases by a factor of 2 to 3 (McGee, On Food and Cooking, 2004, p. 310). Anyone who cooks the onion directly with the vegetables instead of sweating it first will end up with a soup that tastes flat, even though all the ingredients are there.
The Thermomix® TM5, TM6 and TM7 (since 2024) use 120°C when sweating. The TM31 uses the Varoma setting, as it has no precise temperature display above 100°C. The result is identical: the onion becomes translucent and sweet, not brown. The 30 g of olive oil prevents the onion from sticking to the base.
Floury potatoes instead of cream
The recipe card below uses 250 g of floury potatoes to 900 g of stock. That is a ratio of 1 to 3.6 and the reason the soup turns creamy without any cream. Floury varieties such as Adretta or Bintje contain 16 to 18 percent starch (German Federal Plant Variety Office, Descriptive Variety List for Potatoes, 2023). When blended, the starch swells and binds the liquid.
Waxy potatoes contain only 10 to 12 percent starch and stay grainy. If you use waxy potatoes you will need cream or cream cheese to bind the soup. With floury potatoes that is not necessary. The soup thickens on its own.
Blending gradually prevents splashing
The card says 1 minute, gradually increasing from speed 5 to 10. That is not the same as running at speed 10 for 1 minute directly. Gradual means the Thermomix® starts at speed 5 and raises the speed steadily up to speed 10. This prevents hot soup from spraying out of the lid and gives a more even creaminess.
Blending immediately at speed 10 risks leaving coarse chunks around the sides while the centre is already over-processed. The gradual increase draws everything downward before it is chopped.
Frozen vegetables: add straight from the freezer or thaw first?
Frozen carrots, peas or broccoli can go straight into the mixing bowl after the onion has been sweated. The cooking time stays 20 minutes at 100°C on speed 1. Frozen vegetables are blast-frozen immediately after harvest and their vitamin C content is often higher than that of fresh produce stored for 3 days (Verbraucherzentrale, Frozen Vegetables Tested, 2021).
Take care with frozen spinach: it releases a lot of water as it thaws. Reduce the stock by 100 to 150 g when using 200 g of frozen spinach, otherwise the soup will be too thin.
Chunky or creamy: your choice
The main method in the recipe card below gives a blended soup. For a chunky version, skip step 5 (blending) entirely and instead run 10 seconds in reverse direction at speed 1. This combines the ingredients without breaking them down.
For a half-creamy soup with texture, blend for just 30 seconds at speed 5 to 7 instead of 1 minute up to speed 10. Visible pieces of vegetable will remain.
Low-carb variation without potatoes
Replace the 250 g of potatoes with 200 g of cauliflower. The soup will be less creamy, as cauliflower binds less effectively than potato starch. After blending, stir in 2 tablespoons of cream cheese (10 seconds in reverse direction at speed 1) for a silky texture.
The stock ratio stays the same: 900 g of stock to 650 g of vegetables (150 g kohlrabi, 200 g cauliflower, 300 g carrots). Less stock makes the soup too thick, more makes it watery.
Freezing and storing
Blended vegetable soup freezes brilliantly. Portion it into 500 ml containers and freeze once cooled. Keeps for 3 months. Blended soups retain their texture better when frozen, as no cell structure remains intact. Chunky vegetables turn mushy due to ice crystal formation inside the cells (German Nutrition Society, Freezing Food Fact Sheet, 2022).
Thaw in the fridge overnight and reheat for 8 minutes at 80°C on speed 1. In the fridge the soup keeps for 3 days.
Stock ratio as a rule of thumb
The card uses 900 g of stock to 700 g of vegetables, a ratio of 1.3 to 1. If you use more or less vegetables, keep the ratio the same:
- 500 g vegetables → 650 g stock
- 700 g vegetables → 900 g stock (as in the recipe card)
- 1000 g vegetables → 1300 g stock
Less stock makes the soup too thick, more makes it watery. The 1.3-to-1 rule works for any combination of vegetables.
Leek as an optional ingredient
The recipe card below marks leek as optional. 1 stalk of leek (about 150 g) adds a mild onion flavour and green colour. Slice the leek into fine rings and add after blending, then cook for a further 3 minutes at 100°C on speed 1.
Leave it out for children who do not like leek. Replace it with 1 extra carrot (100 g) for a touch more sweetness.
Sausage addition for children
After blending, stir in 200 g of frankfurters cut into slices. Warm through for 3 minutes at 80°C in reverse direction at speed 1. Do not cook at 100°C or the sausages will burst.
The sausages add a savoury note and make the soup more appealing to children who would otherwise refuse vegetables.
More soups made with the Thermomix®:
- Pumpkin Soup
- Potato Soup
- Tomato Soup
- Goulash Soup
- Creamy Leek Soup
Classically creamy rather than chunky: why our ratio works
Some recipes use 800 g of water to 1,250 g of vegetables (kohlrabi, potato, carrot, mushrooms, peas) and cook the soup chunky in 13 minutes at 100°C in reverse direction. Others opt for 800 ml of stock, 700 g of vegetables and 100 g of creme fraiche when blending. Our recipe needs neither cream nor creme fraiche: 900 g of stock to 700 g of vegetables with 250 g of floury potatoes binds the soup on its own. The 1.3-to-1 ratio is the rule of thumb that works for any vegetable, from summer courgette to winter parsnip.
Goes well with: Bread rolls.
