Coarsely chop the walnut kernels. Put the celery and carrot salad in a large sieve and drain. Clean lamb's lettuce, wash thoroughly several times and also drain. Peel and finely chop the onion. Mix yoghurt, mayonnaise and diced onion. Season with salt and pepper.
Wash apples, dab dry and grate roughly when unpeeled. Mix with lemon juice, then add celery and carrot salad, walnut kernels and salad dressing and mix well. Season to taste with salt and pepper. Arrange in a bowl with lamb's lettuce. Serve with roasted ham
With 8 people: