Trim excess fat from ham; cut ham into small cubes. Cook peas in lightly salted boiling water for 5 minutes. Drain, reserving cooking liquid. Leave peas to cool.
Coarsely grate carrots. Quarter cucumbers lengthwise, scoop out seeds with a small spoon and cut flesh into small pieces. Cut pickled onions in half. Place carrots, cucumbers, pickled onions, tomatoes and peas in a bowl.
To make creamy dressing, whisk mayonnaise, yogurt, mustard, lemon juice, sugar and 3 tablespoons reserved cooking liquid in a bowl. Add salt and pepper to taste.
Stir dressing into salad. Distribute among serving bowls. Add lamb's lettuce and alfalfa sprouts.