Boil potatoes for 15-20 mins until
tender. Meanwhile, place the milk in
a frying pan; season well. Bring just to
boiling point, then add the fish, skin side
down. Gently cook for 5-10 mins, until
the fish is translucent and just flaking.
Remove the fish from the milk, discard
the skin (this will come away easily) and
milk, then wipe out the pan. Break the
fish into large flakes, then drain on
kitchen paper. When the potatoes are
done, drain, return them to the pan, then
briefly heat on the hob to dry them out.
Mash well, stir in the mustard,
mayonnaise or tartare sauce, spring
onions, lemon zest, parsley and flaked
fish, then season well.
Using floured hands, divide mixture
into 8, then shape each portion into a
large patty. Put the flour, beaten egg and
breadcrumbs on 3 large plates. Dip each
fish cake in turn into the flour, egg and
finally the breadcrumbs, shaking off any
excess as you go. Sit the fish cakes on a
piece of greaseproof paper while you
prepare the others. Heat the oil in the
frying pan, then fry the fish cakes in
batches for about 3 mins on each side,
until golden and crisp. Keep the first
batch warm in the oven while you finish
cooking the rest.