Put the dressing ingredients into a
bowl, whisk well, then set aside. The
dressing can be made a day ahead.
Mix together the celeriac, carrots, spring
onions, bok choy and peas. Sprinkle
with a little salt, mix again and leave
to stand for 5 mins.
Pour the dressing over the vegetables
and mix well. Stir in the parsley and
coriander just before serving.