Method

1. Chop all the vegetables
2. Heat the oil in a large saucepan, add the onion and cook for five minutes
3. Add the carrots and celery, cook for two minutes
4. Stir in the lentils, herbs, stock, puree and pepper and bring to the boil
5. Cover and simmer for 20 minutes until the lentils are soft
6. Stir in the courgettes and mushrooms and cook for a further 10 minutes
7. Transfer to a casserole dish for serving