Dice the ham and puree it with the cutting stick of the hand mixer. Add cream and sherry. Season with salt and 1 1/2 tablespoons of peppercorns. Clean, wash and drain the lamb's lettuce.
For the vinaigrette, peel and finely dice the onion. Mix lemon juice, 3 tablespoons of water, sugar and diced onion. Gradually stir in the oil. Season with tomato herb salt and remaining peppercorns.
Add lemon zest strips to the vinaigrette as desired. Arrange lamb's lettuce on plates. Use 2 tablespoons to cut off the cams from the ham mousse, place on plates and sprinkle with the vinaigrette.