Preheat the oven to 190C/375F/fan 170C/335F or gas 5.
Heat a little oil in a roasting pan and add the potatoes and thyme. Roast for about 25 minutes or until golden tossing from time to time.
Season with salt and freshly ground black pepper. Set aside and keep warm.
To make the dressing, pour all the ingredients except the parsley into a small saucepan over low heat. Stir until all ingredients have dissolved.
Add the parsley and check the seasoning. Keep warm.
Heat a large frying pan over medium heat, add the olive oil followed by the Royal Rose radicchio leaves. Toss lightly for about a minute or so until slightly wilted.
Add the spinach and wilt for a further minute. Transfer to serving plates and add the roast potatoes.
Spoon over some dressing and arrange the smoked salmon and lemon slices on top.
Garnish with sprigs of dill, sprinkle with freshly ground black pepper and serve immediately.