Heat oil and butter in a large pan over medium heat.
Add chopped onion and stir fry till it becomes a bit soft.
Add chopped garlic and stir fry for 1 minute.
Add the vegetables, mushrooms and celery stalk. Mix well.
Cover the pan and allow the vegetables to 'sweat" for 1-2 minutes.
Add the chopped tomatoes and beans. Mix well.
Cover the pan and allow the tomatoes to cook for 1 minute.
Add tomato puree, stock and salt.
Bring the mixture to a boil.
Add the pasta, mixed herbs and celery leaves.. Mix well. Cover the pan.
Allow the soup to boil till the pasta is done. This usually takes about 10-12 minutes.
Add pepper and mix well.
Garnish with chopped spring onion or fresh herbs.
Serve the soup with some cheese and your favourite bread.