Scrub the mussels and remove any 'beards'. If an open
mussel does not close when it is tapped, it should be rejected.
Place the mussels in a pan with a cupful of boiling water and
continue heating until all the mussels have opened. Keep the
liquid as stock. Remove the mussels from their shells and cut
them into small pieces.
Remove the skins from the tomatoes by placing them in boiling
water for a minute, then plunge them in cold water. The skin
will now peel off easily. De-seed the tomatoes.
Melt the butter in a large pan, add the olive oil and saute the
chopped onion and tomatoes for a few minutes. Do not allow
the onion to 'brown'. Add the mussel stock and the brandy and
cook slowly. Stir in the flour and then add the milk slowly.
Add a pinch of salt and continue to cook for 3 or 4 minutes.
Place in a blender then back in the pan, add the chopped
mussels and then serve hot.