- Heat a splash of oil and add the onions. Cook until softening
- Add the chickpeas, lentils, tomatoes and celery
- Add the tomato puree and spices, cook for 5 minutes
- Next add the stock
- When the stock is hot through add 2 cupfuls to the sourdough starter
- When combined slowly add back into the soup
- When the vegetables and lentils are softened whizz the soup, add water to reach the desired consistency
- Add the chopped herbs and season to taste.