Take one beetroot and slice it into thin rounds. Put the salmon on a plate (if it is already sliced, then remove the plastic sheets interleaving the pieces, but arrange the slices so that they are evenly overlapping). Grind over a little pepper and lay the beetroot over the top. Cover tightly with clingfilm and put a second plate on top to weigh it down. Refrigerate for up to 24 hours (at least 4 hours).
Cut the rest of the beetroot in half, then slice into half circles about as thick as a coin.
Slice the chives finely on the diagonal. Break the walnuts into three or four pieces each.
Mix the sliced beetroot halves, chives, walnuts, walnut oil and sherry vinegar. Season well with salt flakes and pepper. (Up to this point can be prepared 6 hours ahead).
Just before serving, peel the beetroot circles off the salmon. Arrange the salmon, crumpling it slightly into a nest, on one large or 2 individual plates. Spoon the salad in a pile on top. Drop a dollop of creme fraiche on top. Break off tiny fronds of dill and scatter over the salad. Please credit Xanthe Clay/www.lovebeetroot.co.uk