Brush beet under cold running water and wrap individually in tin foil. Bake in a preheated oven at 220 °C (gas 3 – 4, convection oven 200 °C) on the second rack from the bottom for 70 minutes.
Cut the salmon into small cubes for the remoulade. Set aside a handful for the garnish.
Clean and finely dice the spring onions. Remove seeds from cucumber, finely dice, season with salt, drain in colander. Hard boil the eggs, rinse, peel and chop finely. Cut the chives into rolls.
Mix the egg yolks with the mustard, 1 pinch of salt and the vinegar. gradually add the oil with the whisks of the mixer until a mayo is formed. Fold in the spring onions, yogurt, salmon, cucumber, chopped eggs and 2/3 of the chives, perhaps seasoning with salt and pepper. Garnish with remaining salmon cubes and chives.
Remove beet from oven, remove foil, score tubers crosswise, bring to table together with remoulade. If desired, offer separately pickled salmon with it.
Tip: As an alternative to fresh chives, you can also use the freeze-dried.