Boil potatoes in salted water for 8 mins
until just tender, then drain and keep
warm (they will absorb the dressing
better than cold potatoes). Meanwhile,
steam the beans in a steamer over the
potatoes for 4 mins. Keep a close eye on
them as you want them to be just tender
rather than soft. Cool the beans under
the cold tap to keep their colour.
Mix the dressing ingredients in a bowl.
Add the warm potatoes and beans, and
toss really well to coat in the dressing.
(Warm potatoes absorb the dressing
better than cold ones.)