Drain the celery salad. Chop walnuts. Wash the chives, dab dry and cut into fine rolls. Peel and finely dice the shallot. Mix yoghurt, salad cream, shallot and half of the chives and walnuts.
Season to taste with salt, pepper and sugar. Peel, quarter and core the apple and grate it into the sauce. Fold in celery as well. Spread the Waldorf salad over the slices of pork and roll them up. Clean, wash and drain lamb's lettuce and frisée lettuce.
Arrange smoked pork rolls on plates and garnish with salad. Serve sprinkled with remaining walnuts and chives.