Serve with some crusty bread and a slice of favourite cheese.
Peel and finely chop the carrots and onions, chop the celery sticks and break the cauliflower into small florets.
Now melt the butter in a large heavy-bottomed saucepan, add the vegetables and stir to coat with the butter. Cook the vegetables over a medium–low heat, stirring occasionally, until they start to soften, about 10 minutes.
Add the stock and season with salt and pepper. Bring to the boil, then reduce the heat and simmer for 30 minutes.
Strain the vegetables, reserving the liquid. Then purée and return to a clean saucepan. Add the reserved cooking liquid and then stir in the yogurt. Reheat gently but do not let it boil.
With local tomatoes now in abundance, this is an ideal time to make a pot of summer tomato soup. This recipe produces a thin, flavoursome soup with just a hint of basil. Just right for a light lunch with some crusty bread.