Orange wash, dry and peel thinly. Halve the orange and squeeze it. Mix the juice with vinegar, oil, salt and pepper.
Clean, wash and cut the spring onion into rings. Coarsely chop the nuts. Peel and finely grate horseradish.
Cut the mozzarella and beetroot into slices as thin as possible and layer them alternately on plates. Sprinkle with spring onion rings, horseradish and nuts and drizzle with orange vinaigrette.