Peel oranges so that the white skin is completely removed. Remove the fillets from the parting membranes. Squeeze juice from the rest of the oranges. Chop the nuts. Wash and sort the lamb's lettuce. Arrange some lettuce, a slice of turkey breast and orange fillets on plates.
Mix the orange juice and vinegar. Season with salt, pepper and sugar. Whip the oil into the mixture. Drizzle on the salad. Sprinkle with chopped walnuts and nut quarters and serve garnished with orange wheels