Place beets into a large pot, cover with cold, lightly salted water, and bring to a boil. Reduce heat, cover, and simmer until beets are soft and can easily be pierced with a fork, about 40 minutes. Drain and rinse under cold water. Peel and cut into cubes.
Heat oil in a skillet over medium heat. Cook and stir smoked tofu until hot, 2 to 3 minutes. Combine tofu, beets, and apple in a bowl.
Mix yogurt, horseradish, and maple syrup in a small bowl and season with salt and pepper. Pour over salad and mix well. Let stand until flavors combine, about 15 minutes.