Mix the white wine vinegar and sugar with 25ml cold water. Put the fennel, dill and peppercorns in a small bowl, then pour over the liquid, making sure the fennel is fully immersed. Cover and refrigerate for 2 hours.
Mix the crème fraîche with the orange zest in a small bowl and season. Refrigerate until needed.
Spread the créme fraîche over a plate, slate or board and layer with the salmon. Scatter over the pickled fennel, drizzle with a little of the pickling liquid and serve garnished with the remaining dill.