By Fraser Reid
Harissa is the main flavour of this mixed vegetable soup. We only use a teaspoonful but the smoked chilli paste carries so much wonderful flavour that it can turn any ordinary dish into a masterpiece.
Heat a pot on a medium-low heat and add the oil or butter. When it’s hot, add the onion, carrot, courgette and garlic and fry for 5–10 minutes until they soften slightly.
Put in the sweet potato and harissa and give everything a stir.
Pour in 900 ml of boiling water and the passata,