Saffron is expensive, but I do think that it’s a vital ingredient when making fish soup and you only need a very small amount. It adds colour and a distinct delicate flavour.
Wash the mussels in cold water, scrubbing the shells. Pull away the fibrous beards and rinse thoroughly to remove any sand. Discard any broken ones.
Heat half the olive oil in a large pan. Add the onion, garlic, fennel and carrot and gently cook for 10 minutes. Add the tomato purée, star anise, saffron and cayenne pepper and cook for 2-3 minutes. Add the white