asparagus stems by holding the stems and quickly bending them. the woody part will snap off.
tie the stalks with string. half fill a deep sided narrow pan with boiling water, add salt, then stand the asparagus in the pan and cover. the tips are then steamed. simmer until just tender, about 4–5 minutes. drain and leave for 1 minute for the steam to evaporate.
add the asparagus to the pan with the potatoes. now add a knob of butter and the chopped herbs. gently toss to coat. season, cover and keep warm while preparing the sauce.
mix together the cream and the zest from the lemon and set to one side.
when the 