Choose a new cookbook worth up to £28 when you subscribe to our magazine.
Heat oven to 200C/180C fan/gas 6. Boil the potatoes in a large pan of salted water. Bring to the boil and cook for 15 mins, or until tender. Drain and set aside to cool.
Meanwhile, zest the lemon, set the zest aside and thinly slice half the lemon. Put the salmon on a baking sheet, season and top with the lemon slices. Roast in the oven for 12-15 mins, until just cooked through. Leave to cool.
Mix together the crème fraîche, dill, parsley, mustard, the reserved lemon zest and one squeeze of the remaining lemon half. Toss together the cooled potatoes with the onion, radish and dressing. Flake over the salmon and season. Take the part-squeezed lemon half with you to squeeze over just before eating.