Prepare the mussels by cleaning them under cold water.
Debeard the mussels by pulling the membrane or ‘beard’ down towards the hinged end of the shell until it comes off.
Of any muscles are open, tap them on a hard surface, Living ones should close back up so discard any that stay open.
Add the mussels to a large lidded saucepan.
Add cider, cover and steam on a medium heat until all the shells open, then remove from the pan.
Strain the liquid and set this aside along with the mussels.
Put the pan back on a media to high heat, add the chorizo and cook until browned and crispy.
Add the shallots , celery , garlic , capers and bouquet garni, cook until soft.
Pour the reserved cider stock over the chorizo and vegetables and cook until reduced by half.
At this point stir in the clotted cream and chervil or parsley,return the mussels to the pan and bring everything to the boil, season with salt and pepper.