By Jane Grigson
Cooks in Normandy will sometimes vary their accustomed vegetable soups by adding mussels and leaving out the cabbage. Mussels go particularly well with pumpkin, which on its own is a favourite autumn soup far beyond the boundaries of Normandy. In its simplest form, pumpkin soup is just a purée let down with milk or milk and water and seasoned according to your taste - and age - with salt and pepper or with sugar. In this recipe, extra vegetables make a sturdier partnership with mussels.