Heat 1 tbsp oil in a large saucepan and fry the onion, carrot, courgette, potatoes and celery for 10 minutes until softened.

Add the garlic and half the Walnuts then add the stock, simmer, covered for 10minutes.  Puree with a stick blender or in a liquidiser.

Heat the remaining oil in a small frying pan and fry the remaining Walnuts and rosemary for 2 minutes until golden. Sprinkle over the soup to serve.