Heat the olive oil or butter in a pot over a medium-low heat. Fry the onion and garlic for 5–10 minutes until they soften slightly.
Add the carrot, courgette, cashews and fresh coriander to the pot, mixing everything together.
Pour in a litre of boiling water, crumble in the stock cubes and bring it all to the boil. Turn down the heat and simmer for 20 minutes.