In a small bowl, add sea salt and pepper and the shallot. Add the vinegar and oils. Whisk to emulsify. Stir the herbs in and set aside.
Preheat the oven to 350 F and prepare a baking sheet covered with parchment paper; set aside.
Place the potato slices on a working surface in front of you. Brush them with olive oil. Flip them onto the other side and brush with oil again. Season with salt and pepper.
On the baking sheet, arrange the potato slices into concentric circles (they will overlap on top of each other) to form a galette. Make 6 galettes like this and season with a dash of nutmeg.
Bake the potato galettes for 20 minutes, or until they are golden in color.
In the meantime, take 6 appetizer plates and make a bed of mâche on each.
Heat 1 tablespoon olive oil in a non-stick frying pan. When warm, cook the scallops for a few minutes on each side (I like to keep them on the rare side). Season with salt and pepper.
Remove from the heat and slice them into circles.
Arrange the galettes on top of the mâche and add the scallops on top.
Add slices of radishes.
Add the Parmesan cheese and hazelnuts.
Drizzle with the vinaigrette and serve.