Mussels are richly flavoured, succulent and not expensive. The golden rule is to discard any not tightly closed or that do not close when tapped before cooking, and any that remain closed after cooking. Simply steam mussels until their shells open up.
This is my version of moules marinière, the classic dish of steamed mussels with flavoured cooking juices. Allow 500g (1lb) of mussels per person; the shells take up bulk and there will probably be some to discard.
Discard any mussels that are cracked or open and stay open when tapped. Wash the mussels in plenty of cold running water to remove any trapped sand. Scrape off any barnacles, pull off the beards and scrub well.
Put 2 chopped shallots and some parsley stalks in a large pan with 300ml (½pint) dry white wine, black pepper and the mussels. Cover and shake over a high heat until the shells open; it will take less than 2 minutes.
With a large spoon, transfer the mussels to a colander set over a bowl. Discard any mussels that remain closed. Put the remaining ones into a large warm serving * bowl. Cover with foil and keep warm and moist.
Strain the cooking liquid into a saucepan and reduce over high heat by about one third. Whisk in 50g (2oz) unsalted butter, a large handful of chopped parsley and some black pepper and adjust the seasoning if necessary. Pour over the mussels and serve. Chunks of good crusty bread are the only accompaniment necessary.