Break away the thick woody ends from the asparagus and peel away any tough skin. Plunge into salted boiling water for 2 minutes, remove and place into an ice bath to cool, then drain and set aside. Boil the brussel sprout outer leaves for 2 minutes, drain, plunge into ice water, drain and hold.
Remove the broad beans from their pods, place into boiling water and cook for 30 seconds. Remove and place into the ice bath, then pop the bright green beans out from their skins. Boil the peas for 1 minute, remove to an ice bath to cool then drain.
Make the dressing by whisking together the Dijon mustard, a little chopped chervil, red wine vinegar and 3 tablespoons of the olive oil. Season well then lightly dress the asparagus, broad beans, peas and torn parsley.
Present the ocean trout on the top with a scattering of the brussel sprout leaves and extra chervil sprigs.