Boil eggs in boiling water for about 10 minutes until hard. Quench cold, peel and cut lengthwise into slices. Clean and wash the salad and watercress. Drain artichoke hearts and cut into thin slices.
Wash lemon hot. Rub the peel thinly, halve the lemon and squeeze the juice. Mix juice, peel, some salt, pepper and sugar. Whip the oil into it. Mix salad, watercress and some vinaigrette.
Arrange on plates with prawns, egg and artichoke slices. Sprinkle with the rest of the vinaigrette and serve.