- Peel black radishes and dehydrate peelings overnight in 150-degree oven. Grind dried peels in spice grinder or blender to make dust. Set aside.
- Dice peeled radishes and simmer in heavy cream with salt until very soft. Cook until cream has mostly disappeared. Purée radish and cream in blender. Add lemon juice and chill in refrigerator.
- Season beef well with salt and pepper. Sear in hot cast-iron pan on all sides and immediately remove from heat. Cool in refrigerator.
- Slice tenderloin very thinly. Cover plate with sliced beef and dollop cold black radish purée around plate. Scatter apple and grate fresh horseradish over everything. Finish with black radish dust, drizzle of olive oil, and sea salt.