This particular batch of mussels was a bit barnacly. They needed cleaning; use the side of your potato peeler, it doesn’t take long. Honor took this photo below, as I was cleaning them.
For four people as a main course you will need two or even three kilos of mussels – a bit less as a starter. I doubt that you’d really want to cook this for more than four; you’d need a really big catering sized pan and a gas burner capable of getting it hot.
Finely chop two medium onions and crush a couple of cloves of garlic. Soften these gently (and completely) over a low heat with plenty of butter. Add just one good glass of dry white wine and bring it up to a ferocious boil with the burner on its highest available heat. Tip the cleaned mussels into the pan and put a tight fitting lid on top. Every minute or so remove the lid and quickly stir the mussels, or give them a really good tossing-shake. You will find the ones at the bottom cooking more quickly – so mix them up a bit. They should take no more than two or three minutes, but are certainly done when the majority of the shells have opened and you can see the pale orange mussels inside. They will quickly overcook, so err towards speediness.
Using a slotted spoon take the mussels from the pan and dish them up into big deep soup bowls. It may seem a daunting number, but remember, the bit you eat is actually very small.
Now add a scant glass of double cream to the cooking sauce left in the pot. Taste it, and add a little lemon juice, salt and pepper. Keeping the heat on high bring it quickly up to the boil. As quickly as possible, ladle a little of this thin white broth over the mussels, using a sieve if you have a fear of any grit making it onto your plate. Pour the rest into a gravy jug, for pouring and slurping later.
I’d normally look for thick slices of crusty bread cut from one of those handmade, white loaves – but most recently had only soft white baps to hand. They were an amazingly good pairing. Either/or will be necessary for mopping up the soupy sauce at the bottom of the bowl.