New potatoes should usually be boiled and cooled before making this kind of salad dish, but I much prefer them roasted - with cripsy skin and melt in the middle soft centres. This dish is incredible flexible in terms of what is added to the potatoes. Here I've gone for blanched and cooled green beans, finely sliced spring onions and rocket - but that could easily be blanched and cooled broad beans, finely sliced regular onion or onion chives and a handful of herbs such as tarragon.
The dressing is a light mustard vinaigrette. Perfect for taking to a BBQ.