Gently boil the beets until tender. Drain and cool until safe enough to handle. Slip or peel off the skins, and then cut each beet in half. Cut each half beet into thin slices and set in a bowl. Add the oil, vinegar, honey, horseradish, dill, salt and pepper and toss to combine. Cover and refrigerate beet salad until needed.
Preheat the oven to 375ºF. Place the potatoes in a pot and cover with cold water. Line a baking pan with parchment paper. Set in the fish, drizzle with orange juice, and season with salt and pepper. Boil the potatoes until just tender; bake the fish 12 to 15 minutes, or until just cooked through.
To serve, divide and place some beet salad in the centre of each of 4 plates. Set a piece of salmon on top of the beets. Divide and surround salmon with the boiled potatoes. Set a dollop of sour cream on top of each piece of salmon. Garnish with dill sprigs and serve.