Cut bacon in half crosswise. Wrap each prune with bacon and secure with a toothpick. Heat the clarified butter in a frying pan. Add bacon-wrapped prunes and brown on all sides until crispy. Remove prunes from the pan and keep warm. Deglaze pan drippings with vinegar and season with salt and pepper. Keep warm.
Pick over the lamb's lettuce, trim, rinse and spin dry. Peel the onions and cut into rings. Rinse pears, cut into quarters, remove seeds and cut into wedges.
Arrange lamb's lettuce, onions, pears and prunes on plates. Drizzle with the warm dressing and serve immediately.