1. Slice beetroots and apples into thin round slices using a mandolin.
  2. Using a ring cutter, cut out the apple slices to make them the same size as the beetroot.
  3. To prepare the dressing, mix mustard with maple syrup. Add white vinegar, olive oil, and salt. Mix well.
  4. To assemble, toss apple and beetroot onto serving plates. Add dressing and sprinkle crushed roasted hazelnut.
  5. Serve immediately and enjoy!