Set a large pot/casserole over high heat, add the water and the stock and bring to a boil. Add the carrots along with the celery, onions, potatoes, tomato paste, chilli flakes and the oil and bring back to a boil.
Simmer with the lid on for 15’ and then add the courgettes, parsley, bay leaves, coriander and thyme, and season with the salt and pepper, cooking for further 15’.