Heat the oven to 425F, with a large 12” cast-iron skillet in the oven. Scrub the beets until clean, trim the stems to about ½'' and trim or peel away any hairy/gnarly parts.

Cut the beets in halves or quarters, depending on their size. Set aside one small beet. Toss the rest of the prepared beets with the olive oil, season with salt and pepper and gently transfer to the heated cast iron skillet, cut sides down.

Roast for 30-35 minutes, turning once, until a knife can slide easily into the thickest part of the beets. Remove from the oven and let cool.

Stir together the yogurt, horseradish, and mustard with ¼ teaspoon salt and pepper to taste. Set aside. 

Melt the butter in a skillet over medium-high heat, adding the cooked kasha and walnuts to the skillet. Cook while stirring, 5-7 minutes, until the grains are crispy and browned. Season with salt and remove from the heat. 

Divide the yogurt mixture between 4 plates. Top each plate with a portion of the roasted beets and sprinkle with the buttered kasha mixture, cucumbers and dill. Thinly slice the reserved raw beet and arrange on top. Serve warm or at room temperature.