Put the clementine zest and juice, vodka and honey in a pan, season and bring to a simmer. Bubble for 10 mins until reduced by half. Add the clementine slices and simmer for a further 5 mins until the clementines are softened and a little sticky. Remove them from the liquid and transfer to a plate. Bubble the liquid until thickened to a glossy glaze.
Heat oven to 180C/160C fan/gas 4. Line a baking tray with foil or baking parchment and place the salmon in the middle – or on an angle to help it fit if you need to. Using a sharp knife, cut the salmon into 8 fillets, cutting through the flesh but not the skin, as this will hold the whole thing together. Cut the thinner end into slighter wider fillets, so everyone gets a similar portion. Brush the salmon with the glaze, making sure you get in between the gaps, and save a little for brushing on at the end. Lay the candied clementine on top, down the centre, and bake for 20 mins.
While the salmon is cooking, make the beetroot crème fraîche by mixing all the ingredients together in a bowl with plenty of black pepper and a little salt – save a few chives to sprinkle on top. When the salmon is cooked, reheat the remaining glaze, adding a splash of water if it is too thick, and dab it over the top (wash the brush first as it will have come into contact with the raw salmon). Serve the salmon and sauce as part of a buffet, and let everyone dig in.