Bring a thumb of water containing a sprig or two of thyme and a couple of bay leaves to a rolling boil in a large pan.
Drop in the cleaned and de bearded mussels and place the lid on.
After a minute give the pan a shake and cook for a further 30 seconds or so or until the mussels have opened.
Drain over a bowl to reserve the juices and leave to cool.
When cool remove the mussels from the shells and add to a bowl with a handful of toasted coriander seeds some of the cooled cooking liquor, a good dash of sherry vinegar, dill and ground pepper and leave in the fridge to steep.
For the dressing place a blob of dijon mustard into a bowl add a little pickling liquor and mix - slowly add extra virgin olive oil, whisking all the time to emulsify - season and add a few sprigs of dill.
Take some french breakfast radishes and half, slice some apples and rolled in lemon juice to stop them de-colouring - assemble on a plate with fresh radish leaves, the mussels - dress and serve.