Step 1

Heat the oven to 450°. In a large roasting pan, toss the beets with 1 tablespoon of the oil, 1/4 teaspoon of the salt, 1/4 teaspoon of the dill, and 1/8 teaspoon pepper. Cook in the upper third of the oven, stirring once, for 20 minutes.

Step 2

Remove the pan from the oven and push the beets to one side. Add the potatoes to the pan, next to the beets, and toss them with the remaining 1 tablespoon oil and 1/4 teaspoon of the salt. Return the pan to the oven and cook for 10 minutes. Stir the potatoes and beets, keeping them separate; return the pan to the oven.

Step 3

Meanwhile, oil a baking sheet. Put the salmon on the baking sheet and sprinkle with 1/4 teaspoon of the salt, the remaining 1/4 teaspoon dill, and 1/8 teaspoon pepper. Put the pan in the oven with the vegetables (after you stir them at the end of Step 2). Cook until just done, about 10 minutes for 1-inch fillets.

Step 4

Meanwhile, in a small saucepan, bring the cream just to a simmer. Remove from the heat and whisk in the horseradish, the remaining 1/4 teaspoon salt, and a pinch of pepper.

Step 5

Stir the beets and the potatoes together. Serve the vegetables topped with the salmon and the horseradish sauce.