Wash lamb's lettuce and drain well. Clean mushrooms and slice them.
Heat 2 tablespoons oil in a pan over medium heat. Sauté mushrooms for 3 minutes, add diced ham, and fry for 2 more minutes until crispy.
Peel and slice the hard-boiled eggs.
Finely chop onion and fresh herbs, then whisk with 3 tablespoons oil, 2 tablespoons balsamic vinegar, salt, and pepper to make dressing.
Divide lamb's lettuce and egg slices among 4 plates. Scatter the fried mushrooms and ham on top, drizzle dressing over, and sprinkle freshly ground pepper on top.