• 110 g/4 oz butter
• 2 large onions, peeled and very finely chopped

Melt the butter and in it cook very gently the onions and garlic until pale golden. Add the Pernod, allow to froth, then pour in the white wine. Add the herbs. Bring to the boil and simmer gently for 15 minutes, uncovered. Add the chicken stock and reheat.

Put the mussels in a large pot and strain the soup on to them. Leave the onion in the sieve, because it’s going back into the soup.